The only one I get now regularly is MRH. I have them all. I only buy a mag every now and then, as they really don't cover what I'm interested in lately.
I do have pretty much complete collections of both MR and RMC, going back to the 1930's. I find many of the articles in the MR's from the 1980's backward are very much as relevant today as they were then. Good modeling techniques have no expiration date. Same with RMC, although their articles have decreased in value to me as well.
Content quality wise, this is how I have the current offerings ranked;
1. Narrow Gauge and Shortline Gazette
2. Railroad Model Craftsman
3. Model Railroad Hobbiest
4. Model Railroader
IMHO, at one time, during the editorships of first John Page, and then Lynn Westcott, MR was the finest model mag on the market. The content since then has become almost totally useless to me. I have to look at each issue to see if its worth buying or not. RMC has changed very little on its content over the years. It has always been geared more to the craftsman side of the hobby, and always has been one of my favorites. MRH, again IMHO, hasn't been around long enough to really establish an identity. Its getting there, but not quite yet.
The Gazette, has been always geared to the craftsman side of the hobby even more so than RMC. While their "history" isn't as long as MR or RMC, their content has been some of the best ever offered. If there's something I'm looking for, and its not in any of the others, I know I'll find it, or something very similar in one of their issues. If you guys haven't looked at one, you need to.