I love the older Marx stuff. I think that is why I also like the Marklin Maxi pieces. They have that old tin toy look about them. But I don't like the prices of any of it. My wife cringes when I buy pieces. My most recent edition was a flat car with an actual cookie on it as the payload. It is from 8 years ago and still in the package, unrun. It was made for the anniversary of a bakery (I think in Germany?) and there are very few pieces. My cookie has a crack in it, but still inside the original wrapper.
A friend of mine was a Lionel distributor, he used to ship all over the nation. When he closed his warehouse I was invited up before he sold everything off. I wondered around the aisles of train boxes, but I couldn't bring myself to buying any of it. I just wasn't interested in that size train. Its great stuff, and he had a lot of very collectable pieces that I could have bought for a song and resold, but I just didn't want to go through the effort to do that for something I really wasn't interested in.
My former partner had a large HO set up. It took up 1/2 his basement. When he died it all was willed to his son, but I suspect it is still in the basement. It was the largest HO collection I've ever seen. And his set up was amazing, absolutely complex with several mainline loops and multiple levels. He was quite a craftsman and built most of the pieces from scratch.