I have yet to try Thumper, but I can certainly vouch for Pinball FX, particularly if you are or have been a fan of pinball in real life. The physics feel about right, the tables are entertaining/challenging and you get the bonus of sharks, planes, knights, zombies and other characters thrown in for good measure around the outside of the table, that provide entertainment when you lose a ball.
I would wait until Thumper is on sale, it's a cool game but it doesnt feel like the price is justified. I also found pacing at the beginning very slow, and the game is boring for the first few levels.
Pinball Fx 2 is fantastic, mind you, you will spend much more on it than asking price because there are DLC tables to buy (and you will buy them, believe me 😉 ) The main game comes with 3 and I think it is a good variation of themes and difficulty, I love Mars table. This game have a ton of replay ability if you like pinball. Definitely worth buying it.
im number 16 in the world for pinball Fx ...so yes its well worth the money ....but seriously its worth the money... the walking dead is an amazing table to play on