I say "steam," but reality dictates differently. For one, I model in N-scale, so steam is pretty expensive (at least compared to what you can get sometimes in HO). But on the whole I prefer steam and would prefer to model steam era (or transition). After all, steam locomotives are REAL locomotives! Not like the namby pamby diesel things with all of their fancy computers and GPS and dynamic brakes and such. It's gettin' ta where ya don't even need no engineer to run dem diesel loc-ees. Why, back in MY day we didn't have no diesel loc-ees. In fact, we didn't even have steam 'cause it hadn't been invented yet. All of our trains were run on DIRT and WE LIKED IT! Then some fancy city folks came and did some of that PROGRESS and LOOK WHAT IT DID FER us: a lot of smoke and noise. Dad burn city slickers and their fancy ways...
Uh...sorry... I like steam locomotives, though. And if I had the money and if I could buy models that ran well in N-scale, then I'd go all steam. Perhaps one day I may make the switch to HO...
Oh, Bill... A "diesel" is the opposed of a "thatsel."