My MMO experience consists of four months of WoW and five months of TOR. As a game, TOR is a wholly inferior carbon copy of WoW ("Then why did you play TOR longer than WoW, mx?" Shut up, I don't know). As a singleplayer RPG...well.
None of the Mass Effect titles took more than 30 hours to complete, and the second and third had a fair number of really great moments throughout. Act I of a given storyline in TOR took something like 50-60 hours to complete, and the great moments were spread very, very thinly. Will that work for you? It may; it takes a while for the grind to become a grind, and I didn't mind leveling until I was taking my second character through Hoth, when I burned out on that completely.
But really the answer is, they're giving out free time and passes like they're candy (I'm sure this means their numbers are healthy, smirk), so PM me your name (doesn't have to be your real name, but they want it in the form) and email address and you'll get a seven-day free trial. Or pester anyone who's subscribed, they should be able to do the same.
I recommend the Imperial Agent, as its story is easily the strongest of those I've seen.