It's always single-cones for me - tricones just don't do it for me. I got a Regal steel-body single-cone from the States. Checking it against the Dean and Johnson equivalents, it beat the crap out of both of them. A friend has an Ozark steel-body which is also an OK instrument. Neither can compare to a *real* National, of course, but they're maybe a fifth the cost for half the quality, which ain't a bad deal. :-) Apparently, buying a Quarterman cone to replace the cone it comes with gets you much better sound, but I've yet to try that experiment.

Also check whether it's a steel-body (National) or wood-body (Dobro) sound you're after - they're distinctly different. I agree with Dave that the Fender reso is crap.

If you can get there, there's the London Resonator Centre in Denmark Street. If you know you want a resonator, might as well go somewhere with a decent range of them, instead of your typical local shop that maybe has two at most.

Graham.