It turns out I CAN only have 5 or 6.

My 4 more to your TAF and STTNG:
SS
WW
FT
AFM

Tron for the flashy modern gameplay and great shots, Ironman for the exciting action, Alien Poker to get some early 80's old school gameplay (maybe Gorgar, Seawitch, Centaur, anything early 80's), and Attack from Mars for the wide open playfield and humor.

TS, IM, Whirlwind, SM/AFM

TS - Depth and unique layout.
IM - Fast, great sound and just plain fun
WW - S S game with humor, challenge and best topper ever
SM - Perhaps Sterns best all around game. LOTR is probably better but sucks as a game to play multiplayer, unless you have all night for one game.

AFM could replace SM. Simple, humorous, EVERYONE loves to kill aliens.

Now go shop.

Given your starting point of classic 90's pins, I would add in one or two from the 80's and a few modern ones as well. Budget is a big factor too. Maybe something like:
- Seawitch/Baracora/Embryon
- High Speed/F-14/Taxi
- Lord of the Rings
- Iron Man/Tron/Metallica/Spider Man

Games like Fish Tales, WCS 94, and TSPP are also always big hits and easy to find.

If I had the money today:
LOTR
JP
STTNG
Stargate
SST
SMB

TSPP is great for non-pinheads and kids. They just seem to gravitate towards it. The bonus is that it is a fantastic pin even for the expert player.

AFM
Tron
Flash Gordon
MM
TZ
Congo
TS

How can you stop at just 6? Stand up state name ......I have a problem....

I'm working on mine...

Tron
STLE
LOTR-LE
Hobbit (hopefully at some point relatively soon)

Next up:

IM
not sure after that...if I could fund it would love to get a P3

My current line-up is spot on for me at the moment.

TAF
Metallica
Stargate
LOTR
Quick Draw

I'm at the one in one out spot. I can't decide which pin could go..

I just recently sold a HUO TSPP. Fun game but it just didn't get much love when compared to the other ones there. Whitewater is a very fun game which I owned for maybe 6 months. It was nice and different. Only reason I have IM listed is I want another kick-in-your-pants type fast game in my line up. Sadly, finances have made me pass on a few IMs lately and a great XMLE just this week.

Dang, you, taxes!

My choice would be:
- Bally Fireball (EM)
- Baly Medusa or Centaur (one early SS)
- Stern ACDC
- JJP WoZ
- LOTR

IM is brutal when trying to beat it, but is super fun for the casual player. IM and WCS get played the most by non pinball people in my collection...

AC/DC is definitely one...IM is another...that are both big hits with non-pinheads.

I'd also look at a White Water

MM
MB
CV
TZ
AFM
Star Trek LE

IM - Original
IMVE
IM - Refinery
Mustang Premium/LE
RFM

Honeymoon over for my 2 newest. I am in a much smaller space now and I can still handle a few more but its tight. with that (and some other issues) I was contemplating just having 2. I would keep LOTR and FT from my collection. So that leaves MET, AC/DC and NGG out. Deserted island pin: LOTR

LOTR or POTC
Black Hole
Joker Poker SS
FT or BSD
AC/DC
Black Knight or Firepower

SS
SS
SS
AFM
MB
BBB

WCS (the definition of an approachable game)
Metallica Pro (or another modern Stern)
Something SS between 78-82 (Centaur, Harlem, etc.)
Rad EM (C37, Card Whiz, etc.)

I have a 5-6 collection myself and I'm slowly working my way to where I want to be.

Right now (because things can and do change):

STTNG is a keeper
IM is a keeper
ST Pro is looking that way....especially since they are updating the code
#4 Tron or possibly Avatar
#5 Williams Indiana Jones or maybe something out there like Alien or The Big Labowski.
#6 Probably one of the pins already mentioned in 4 or 5 or maybe something not even official yet like "Game of Thrones" or a new "Star Wars".

I am moving soon, may be looking to scale down. If I had to cut my collection down I think Judge Dredd, Jackbot, Baywatch, Twilight Zone, Terminator 3 and Bride of Pinbot would be the keepers.

That said, I hope I can hang on to all of them.

Like stated above you have some good 90s DMDs for diversity I would add a few new sterns and some older williams.
With Sterns for me it would be pick a from either: Tron, Star Trek, IM, Avatar, and Spiderman

For the older Williams: Scorcerer, Space Shuttle, Pinbot, Taxi, Whirlwind

striker extreme-
corvette-
shack attack-
monopoly-
Harley Davidson-

Interesting. My buddy has 10 pins and I have 16. He asked if I could only keep 4 which ones would I keep? The 13 in my game room are my favorites and are all keepers to me, but if forced to choose only four they would indeed be:
SS
AFM
MB
BBB

RBION
TAF
ST LE
TRON
POTC
AC/DC

I had 6 in my limited space at one time, currently have 5 + a MAME, and it's really tight. If I have to pull a machine out of line to work on something, it's darn near impossible to move in a room that is ~15x9. If I keep the MAME (and I debate that all the time) I have space for 4, and this is the lineup:

TAF
Silverball Mania
Stern Pinball
Target Alpha

Classic DMD, Bally, Stern, and Gottlieb. I think...for a while...I'm done with acquisition. Now I'll start working on making each of them as nice as possible.

If money and space were no object, I'd add TOM and LOTR. Or Black Knight. Or Firepower. Or Paragon. Or....

ACDC
STTNG
LOTR
Aliens
MM
TZ

If I could only have 5-6 pins I would be pretty damn happy.

First off, I wish that I "only" had 6 pins!

Mine would be 3 that I love for their rules and depth:
LOTR
TSPP
WPT

and 3 that I haven't played much, but believe that I would enjoy long term:
AD/DC Premium
MM
TZ

IMHO that would be a really terrible start. Pick one of them, but all three of those means you're going to end up with half your collection sitting there, rarely getting played. They really don't compliment each other, too similar in the long-form grinding play. Which is great if you're in the mood! But tough when when you have a small collection and don't always want to commit to epic games.

My suggestion would be to add some games from different decades. Grab a early Bally, a sys 11, and a modern Stern. Maybe an EM as well, if your up for tinkering. Having a good variety of playing styles is key in a small collection.

RBION
Surf Champ
Dr Dude
BBH
WOZ
Star Race

perfect!

My vote for the next four:

Metallica or Tron
Centaur (or Centaur II, it's cheaper) OR Space Invaders
Johnny Mnemonic
TotAN

Different layouts and strategies, good mix of designers and art, all great games.

If you can swing it, America's Most Haunted. By all reports fantastic.

Shaq Attack...Shaq Fu "I lean on the statue of Liberty when I get tired"
Barb Wire...Don't call me babe!
South Park...how'd ya like to s#^& my #$#(&*
Austin Powers...yeah baby
Starship Troopers...Everyone Fights no one quits!
Twister...Everybody underground now!!!

What a fun crap fest this list is....Just perfect.

Williams ij
Space shuttle
Defender
Sorcerer
Gorgar
That's the ones I have now. Wouldn't mind picking up a ss joker poker

FT
DW
MOPLE
AC/DC
HS2

Except that Starship Troopers is a really fun pin.

MM or MMR
TAF
Spider-Man
Ironman
Bride of Pinot
AcDc or Metallica

Yes I did more and it was too much.

Now I will suffice with five pins and still feel I have too many.

Hey at least they freaking rock and my lineup might be boring to others but to me its the bomb every game is fun and somewhat challenging (ss maybe not).

Tron LE
AC/DC premium
TZ hep
SS hep
Taf

Thinking heavily of adding MM in the future when they are flooded in the marketplace.

If I could only have 6, TAF and STTNG don't make the cut..

Creature, Cirqus Voltaire, White Water, Whirlwind are in for sure.

TSPP and Godzilla round out the 6 I'd pick.

In no particular order:

EBD
Star Gazer
Nineball
Joker Poker
Top Score
Flash Gordon

But, it's easy when that's the kind that you prefer.

What's wrong with a 30 minute game of pinball... that's like, more pinball. How often do you only plan to play only a single game? I always play a few, and longer games are a positive for me, because I love to play pinball.

If that's your dream collection then by all means. I have a friend with TSPP who bought a WPT. It left fast, was just too much like playing TSPP. IMHO in a small collection variety is really important, you can rotate and keep things fresh. Half of my collection being long playing grind games would get old really fast, even if any one of them would be a good add. But everyone has different tastes.

As you can see from my collection I prefer a broad range of eras and styles, choice is nice. I might stay stuck on the same game for a month, but I know I can switch it up any time I want something else.

My 6 would be
SS
AFM
MB
TOTAN
LOTR
SM

Pretty much my linup and Monster Bash.
LOTR,
ACDC
SM
Tron
TS
MB

STTNG
Cyclone
TFTC
TOM
TSPP
FH

I would keep your TAF and STTNG and add for all the non racy pinheads and non pinheads that play your games
3. IM - good players love this game and non pinheads love this game and they can play together
4. WCS - so approachable. The best family game ever? Goal!!!!
5. RFM - different, great humor and video/pinball concept is awesome. Can you imagine all pins like this today?
6. ST Pro - with the new awesome update that is here! (Edit)