You are going to need some button somewhere in order the exit the games arent you?
That's what got me on adding the touchmaster games (mame) to a jukebox I put together for a friend.
Got everything working only to realize there was no way to exit without breaking out a keyboard.
The Touchmaster series is about as good as it gets for touchscreen games in MAME.
Last time I messed around with them, the Megatouch games were limited to ancient versions and they had odd glitches like blank cards.
You might look for Pop Cap PC games in the budget bin.
The Ollies Bargain Outlet near me always has them.
I haven't personally tried them, but I've seen builds on here where people have built touchscreen bartops based around them.