BSD and TS. Mine will never go. Better than A games. I do not care about how many feature, toys, tricks are stuffed in a game. What counts is playability. Set BSD up properly, as you wish: its the most adrenaline pumping game ever, I own it for few years and its still fresh as day one. Huge changes with different steepness angles (mine just shy of 6 degrees, I much better prefer than the regular 6.5), just set it as you prefer. TS is also a really amazing game, with unbeatable lastability: just tweak some standard adjustments, especially lenghten the modes duration, and the game is among the best of the best. The Aurich translite beautifully solves the Alec Baldwin problem.
Those are the most played games in my collection. I personally love both themes, especially BSD, but the gameplay itself is really terrific on both machines.
Talking about value for money, a mention of honour for JM: fix the spinner problem with a slow rotating spinner and this game makes it to the top 10.

Here the enhanced rules for TS:

https://pinside.com/pinball/forum/topic/the-shadow-luppin-rules

For me TS and BSD. Mine, both, will stay here forever, beautiful machines. I would not let them go even for crazy money, they are too good and always keep fresh, which is the most important thing in my opinion. I had TS for over an year and didn't have any issue. It does not look like requiring more maintenance or special care than any other machine of that era.

I own TS and BSD for several years. Both not going anywhere. Both hard amazing games, hard to choose.TS deeper (especially using the Luppin Rules https://pinside.com/pinball/forum/topic/the-shadow-luppin-rules ). But the highest peaks of adrenaline come with BSD: when you manage to triple stack and get big jackpots is AWESOME!
Similar great value: fix the spinner, and JM also is among the very best. A blast to play!

I love difficult games, firstly because I am a good player and secondly because they have much better lasting power. Usually hard games have lower scores, because most people rank games they played just a few times on location. But to appreciate a difficult game you need to play it extensively, much more than an easy or average game. But being on location that means spending quite a lot on a machine that is not very "user friendly" in the beginning, a thing most people do not want to experiment. Hence: few games, bad games, low score.
Now take games like BSD, TS, FG, SKateball: all hard, difficult, long lasting games. And you can have them for a lower price than their real value. Those are the top games in my opinion: hard, long lasting and relatively cheap.