whichever one you think will sell the easiest for your initial spend. if you only have one pin, eventually you will want to swap it out for another

If you don't know how to work on pinball machines, the star trek pro would be your best bet. If you do know how to work on machines, then try to play them all and get what you like the most.

any of them will be a great one game collection

but they are all different and it comes down to the rules on how to play the game
Centaur is easy to learn in a couple of hours
Taxi
Demolition man
Star Trek will take weeks for you to learn the rules and play all its modes

Depth of code on your four choices goes from newest to oldest:
#star_trek
Demolition Man
Taxi
Centaur
Centaur and Taxi you can learn all the rules in a few days. It comes down to execution. You’ll be doing the same thing a lot but they are both great games.
Demolition Man has many goals. With the latest code the claw is a fun and unique toy. You will not beat the Wizard mode in a month unless you’re a great player.
Star Trek is the deepest by far. Each of the six modes shown in the middle of the playfield has three levels. There is a mini wizard mode after you complete all six modes on any level. You will not beat the Five Year Mission (final wizard mode) within a year.

Taxi
Star Trek
Demo Man
Centaur

I like them all but would go ST Pro

I would go Centaur. Maybe Demo Man

If I'm choosing for myself:

Centaur
Taxi
Star Trek
Demo Man

If I'm choosing for you:

Star Trek
Demo Man
Taxi
Centaur

My words coming out of your keyboard - scary!!

ST

All good to great games (I love Taxi) but I would say for a first game Star Trek.

Star Trek pro is a great choice! My favorite stern layout

.

meep, didn't think too hard before I spoke

.

(but also Taxi)

I think this is the way I'd go as well. If for some reason ST was not in really good condition and the Marilyn Taxi was, I'd take it.

Is this the list you narrowed down to? ST Pro and, say, Taxi are widely different?

If you can’t decide between these different styles of games, maybe consider who else will play them at your house.

Go with ST Pro. It's the best of the choices by alot. I'd be concerned with staying power mainly with a first pin. ST will have the most staying power in a lineup. If I owned a ST Pro, I'd probably keep for more than a couple years before moving on. Plus, they hold their value pretty well, so you're not gonna lose much if you resell down the road.

Welcome to the addiction, friend.

I have the same problem as the original poster. I need to buy my first pin and having a difficult time deciding what to get. Fortunately for him, his budget is larger than mine. haha.
Going with the Star Trek Pro sounds like a solid choice for the reasons people have already listed.
The last time I was at the arcade I played Taxi immediately after playing Led Zeppelin Pro. The difference in game play was astounding.