Still using MSTS after all these years, since 2001 at least. Have only branched out to Auran's Trainz 2004 and 2006 recently. On Trainz I use it for it's continous loops and automation features. For MSTS I've gotten into German railroads as I lived there for a couple years. Picked up a German copy of MSTS and a route by ProTrain (the Berlin route). That's really the only thing that kept my interest going in MSTS. That and Maple Leaf Tracks.
Trainz, though, is more user friendly on the consists, but MSTS has the better engineer controls of the two and the most free addons. I think by now they should have replicated all railroads, both model and prototype, known to man.
It was also nice to see the large variety of computer games, all types, being sold in German electronics stores. Coming back to America "all computer games are history, unless you want World of Warcraft." That's coming from GameStop, CD TradePost, Best Buy, etc. C'mon, vinyl records are making a comeback but computer games, particularly the simulator, is a dead genre? Target is the only one with the largest inventory of computer games, but I think as far as simulators go, Walmart and Best Buy will sell Flight Sim X. I even went to Toys R Us and they've ditched their computer game inventory. I think I'm living on the wrong continent (and more reasons than just computer games).
Now that I've got Trainz, Trainsim, Flightsim, Shipsim, Vehiclsim, and Sherlock Holmes Sim I'm going to layoff any new sims and games for a while. I've got enough to entertain me for now.