I'm a conventional guy as well and I focus on Lionel Postwar as it's always been easy to work on. When I first got into the hobby my father and I were buying K-line as well as a little MTH/Railking as it was what was affordable.
Now I stick mostly to Lionel, but a few years back I had the chance to buy a Williams by Bachmann Canadian Pacific passenger set lead by a pair of F3s. I figured I would never afford the postwar version, so I took a chance. I have been very happy with my decision. While I'm not a fan of some of the blocky graphics on Williams freight cars and the glossy finish that seems to be on much of the older Williams stuff, I am keeping my eye on some other engines as affordable substitutions for Lionel Postwar.