Guys correct me if I am wrong!
From my knowledge, the TX is the most basic Legacy, thus no airbags, no abs and fwd (at least in BG), they also have the most basic trim. The TS-R is the top spec 2l Legacy, akin to the GTB, shares alot of the same trim, ABS, 4WD, airbags and some have the Blisten suspension.
As for power, the TS-R makes an easy 10kw more or so.
Bottom line, at one point there was a TX BG4 in my driveway, now there is a TS-R BG5B. Go the TS-R, hands down IMO.