Best CRT? It doesn't matter, pick one with a nice, bright,
crisp display that supports the refresh rate you want at the
highest resolution you'd use. The criteria for gaming with
a CRT is no different than for regular 2D use, except maybe
that some games (like Doom3) are awefully dark and so it
might be useful to have a monitor you can crank up the
brightness on, though there are usually in-game settings for
these things too.
