Ooooh .....difficult choice as I adore both games. I'm going Tommy purely on sentimental/personal reasons. Though I totally get why some people would prefer FT.
Tommy was my first pin 16 years ago, I loved it on location back in 1994 and had to have one. It's a very different feeling game to FT - it's mode based, think TAF rules. A dialed in one plays so lovely. It has several fantastic multiballs and of course the killer blinders toy. The recent Chad code rewrite is a MUST - the blinders are utilised more in game now, some serious rule changes to some modes, just all round polish on bugs, sounds, lighting etc
I love FT. Absolutely killer fun game. Classic. Saying that I have had 2 and sold 2. So I do get tired of it in a smallish lineup. The good news is there are plenty more Fish (Tales) in the sea so not hard to find another.
Availability could be the factor for you in this .... decent Tommy far harder to come by. So maybe go Tommy, lot easier to pick up a FT down the road.