Shadow

Paragon or EBD. They are both hard as nails and never get old. They both have that one more game thing in spades and a surprising amount of depth for their age.

Agree on EBD. When you rarely manage to score every one of the six different Specials on it in a single game you feel like a king. I did it maybe once or twice on mine in 20+ years. And shooting pool has always been a natural when it comes to pinball.

TWDLE. Hard to play and keeps me coming back for more. I love the theme.
TMNTLE is becoming a go to for me also. Hard brutal and fast and generally kicks my arse. Very satisfying when I have a good game. Love the theme!

Houdini, bad for location as it takes more than a few casual games to figure out the rules and shots. Great for the home for the exact same reasons.

Game of Thrones. Pro or Premium. The replay value is fantastic

ST:TNG, a nice variety of shots, plenty of interesting modes and a few hidden features.
I also like the theme but not everyone does

Black Hole, getting multi ball on this one is no easy task. Really like the lower PF
that slopes away from the player, a real classic

Gtb Spiderman, this was my first pin over 30 years ago and still played regularly.
No music but a nice variety of shots and the artwork is top notch

Gtb Sinbad, very common game but one of my favorites. It gets played a lot too.

Much of how a game plays depends on how its set up. I've played all of the
above games at shows and was not impressed in large part because the rubbers
were old and/or the angle was too shallow.

EBD and BK2K

TWD and/or Star Wars Prem/LE.

Both brutal, but always coaxing you to press the start button again.

Whirlwind with lanes wide open is brutal.
Stern Star Trek with fresh rubbers would be my second choice.

This really depends on the era of game you are looking for. If you want newer games, i would say Houdini or TWD. You could also go with just about any JJP game for complexity (WOZ and POTC would be at the top of the list, however). The Shadow or BSD for 90s. Older games would be Flash Gordon or paragon. There are a lot of EM games that could work as well, but only if you are considering high score as the metric (since they obviously arent as complex as newer pins).

Flash Gordon
Stars
Nineball

Definitely TWD with a modern game, personally I'll push the start button on Firepower 100 times in a row chasing that mulitball.

80s:
Quicksilver - Really tough to spell Quicksilver in one ball, but the siren scoring countdown when the ball drains makes the 100s of games you play to achieve it worthwhile.
Paragon, Flash Gordon and EBD

90s:
Shadow, BSD and Fish Tales

Bram Stokers Dracula (30, 30, 30 Million)
Flash Gordon
STTNG (would be epic with modern rules)

You basically described the same type of machines I go for. They have to be difficult, almost punishing for me. The harder the better.
I like to set my tilts relatively tight. Nudging is the best but there are different levels of nudging. Early games are all on 3 ball.
The later games I list are based on how difficult it is to get to the wizard mode and keeps me coming back for more.
Fathom -
Star Trek Bally
Punk
Paragon
Spirit
EK. Set tilt tight and 3 ball.
Dolly (amazing sleeper on 3 ball if you set tilt tight) very difficult to spell “Dolly Parton”. My top gambling game.

Iron Man VE
Tron
Black Knight LE (another sleeper that keeps me coming back for that wizard mode)
Star Wars Premium cartoon art ( I don’t focus on the multiplier and score. Strictly blowing up Death Star and wizard.)
Hot Wheels - amazing rules. Great bang for the buck.
Alien - amazing rules.
RBION-fantastic getting to wizard mode.
GOTLE

During the pandemic, I find myself gravitating to tougher games but single player and going after wizard modes.

All great picks.

I never get sick of playing Alien Star or Paragon. So many flipper kills involved to master and both can be brutal when they want to be.

Barracora is a great player with a great set of rules. I find myself playing it for hours.

Op, you are going to get all kinds of suggestions. Several titles are going to keep surfacing. I would select a few and go play them to see which one resonates with you. My first thought was Flash Gordon. It will kick your ass down the street and around the corner. Still, you will come back for more punishment.

Bow and Arrow. 25 years plus and still really enjoy the game!

I’m surprised how often Alien Star has been brought up. It’s one of those pins that if I can find someone to play against I’ll spend literally hours (which equates to dozens of games) playing until the other player gets bored

In my collection:

Player's Game - AMH. After receiving all the fixes its a smoother playing game (really fixes the jump ramp) with a deep ruleset.

Casual Game - Mystery Castle. It is difficult enough to collect all the items, but it doesn't feel as high pressure. Fun for most anyone to get on and play.

There are tons of great EMs. Games I have spent time with and really like are Atlantis, Grand Prix, and Space Mission. There are tons more. i have also become very fond of early SS games that look, play and sound like EMs. Stars, Joker Poker, and Mata Hari are all great titles.

SW premium (pro is great as well). Lots of modes and different character abilities.

You're speaking my language. Pinball machines don't need all that filler. As long as there is a good layout and good rules and fun to shoot.

I have a 1975 Abra Ca Dabra. It has a symmetrical layout with 2 banks of drop targets with a very good set of rules and can be challenging. I find myself playing it for a good while. It's nice to look at too. There are some great machines from the 70s that can be found.

Ripley's Believe It Or Not. My longest tenured game at over 10 years and there is no end in sight. For a more recent game for me, JJP POTC. Not going anywhere anytime soon. Both have deep challenging rulesets with tons of shot variety that keep me interested every time. I happen to like both themes as well, which doesn't hurt. I wouldn't let a bad theme get in the way of a good game though. Iron Maiden did nothing for me as a theme, but the game was so good I still bought one and the music has grown on me.

I know folks are going to laugh, but Baywatch is an awesome players game. Get past the big picture of the Hoff and play it!

I think EBD is good but I could not justify keeping it because I found it too easy after playing it hundreds of times.

Nearly every game in my collection is set up extremely difficult to minimize ball times. I even have lightning flippers on a few!

My games play fast and have short ball times on purpose. Only exceptions are maybe Elecktra, Mr/Ms pac-man, Fathom and Sharkey's. So yes, you are looking for a lot of the same games that I’ve collected for the last 16 years. Honestly, you shouldn't need long ball times to play a fun game of pinball. My main problem with those games is that once you are really skilled at pinball, your standard setup game of LOTR or WOZ plays so long that on ball 2 or 3, your hands and fingers start to cramp up! (Not kidding!)

Some that I’ve let go of that are very difficult and have short ball times are Tron, Sinbad, and F-14 Tomcat.

Theme is usually not that important in pinball unless you are an operator. There are certainly exceptions (BSD,Tron,TZ) but most often, theme does not matter as much as the raw pinball design matters.

Ugh! Both of those games play FOREVER!

With no ball saves on either game I don't know about forever, but with deep challenging games, to get far into them you do need to play for an extended period of time to see what the game has to offer.

Stern Star Wars and Game of Thrones have had some of the best addicting + Lastability games I’ve had in small collections. Fast, flow, brutality, coupled with one of the best unorthodox rule sets around.

Wonka - difficult as hell, low/mid/far-reaching goals, and rewarding when you progress. Almost 2 years of Wonkin' the Donk and we still love it.

Here are some good EMS that should have lasting power in a collection:
2001/Dimension
Quick Draw/Fast Draw
Jacks Open/Lucky Hand (Joker Poker is a SS followup pin)
Old Chicago
Out of Sight/Far Out
Grand Prix (Williams)
Abra Ca Dabra/Team One
Jumping Jack/Jack in the Box
El Dorado/Target Alpha/Solar City

The above are desirable, fun pins and large production numbers of them were made. Some like Quick/Fast Draw are 2-player and 4-player versions of the same playfield. Some like 2001/Dimension are reply/AAB versions of the same layout, but different rulesets. Some pins had different versions released to Europe, so look them up on IPDB to se all of the versions released. For example:

Jacks Open US - replay
Lucky Hand US - AAB
Lucky Card Exported to Italy

Centaur's layout is hard to compare to other machines. There's nothing else like it, as far as I have been able to tell. At first glance, it may not stand out as anything interesting, but when you play it, it really ties together. It has arguably one of the best shots in pinball (Queen's Chamber double value) where you hit a short semi-orbit over 2 star rollovers, into a captive ball that hits in-line drop targets. There's another small semi-orbit shot that takes you to the upper lanes for advance bonus X. Another couple of targets, one is a long shot that starts multiball and is satisfying to hit (Captive ball target is the other.) Can't forget the 2 other banks of drop targets that have different rewards from hitting them in and out of order. I also like games that have inlane/outlane switching, plus outlane save gates make things interesting. Combine all of this with a up-to-5 ball multiball and Centaur is a point-chugging machine.