Do NOT get one that is to technical. I would stick with the Williams System 11 stuff. That is what I did. I bought one off eBay that doesn't have any issues but is a player not a looker. I'm getting ready to do a shop job on it here soon, then next winter it is getting broken down for a play-field restore and clear coat job.
If you get one that is to complicated, IE, Star Trek: TNG, Indiana Jones, Twilight Zone (all go for good money) you may regret it as you can't work on your pin skill and you may get bored with the game. Also, I've been told by many sources that one pin isn't enough.... so plan on buying another shortly there after.
Games I would recommend from my limited knowledge:
The Machine: BoP (good beginner to skilled pinball) Just watch the center shots
Highspeed II
F14 Tomcat
Black Knight or 2K.
These are all late 80's early 90's that aren't that complicated and are just prior to the Dot Matrix Display days. Good mix of early solid state design and more complex rules than your standard fair 80's SS pins.
My last recommendation is to get with an Operator that still has pins on location and go play them. Figure out if you truly want a pin.
And my last opinion. Virtual Pin ain't got nuphin on a real pin.
-JD-