While there are certainly better CRTs in terms of maximum possible quality when calibrated (The FW900 is this for monitors and I would highly recommend it if you can hook up whatever console you're trying to play by RGB, which you probably can) it is important to note that by far the most important thing to look for when buying a CRT is to make sure that it isn't already damaged goods: You will notice bad convergence or geometry after using a CRT for any length of time and you may not necessarily notice it when purchasing, so pay specific attention to that. You are probably also looking for an aperture grille television hence the repreated recommendations for some kind of Trinitron (note that not just Sony makes Trinitrons). Any Sony KV will do fine as long as it's in good shape and it's made somewhere in the last fifteen years (you can go older but you'll start noticing a difference).
However, considering the size you're looking for, you may be better off buying a high-end CRT monitor and using an RGB box to hook up your consoles. There are literally hundreds of thousands of IBM P275s available if you look for them; they are 21 inches, they have fantastic colour quality and they are absolutely great for playing anything. They are not HDCP compliant despite being capable of 1080p so you can't use them for your PS3/X360 (well, you can, but you'll either need an HDCP stripper or component cables) but that's really the only hitch. I have four of them and other than the one that I bought in 2002 I haven't paid more than $50 for any of them and they've given me no problems.
A light gun won't work with certain CRTs either, specifically ones that attempt to deinterlace 480i.
