My friend in our weekly jam plays with an Eddy Finn banjolele concert that has resonator back. Most of the songs he plays are with clawhammer, and it is loud enough for our small jam.
My 1930's "John Grey & Sons" soprano banjolele, which is a fairly generic wooden-pot banjo with a resonator plate on the back, does a good job for claw-hammer tunes and is plenty loud enough for most things when the skin is good and tight (I've recently replaced what was probably the original skin, which had torn at the edge and wouldn't tension properly). I'd suggest any instrument in playable condition would suit, clawhammer and the "banjo sound" go together hand in hand
Some possibly mis-informed persons might suggest fitting steel strings. I'd not recommend this. If you don't have geared tuners, maybe on an older instrument, they can be extremely difficult to tune accurately, also they will put a much greater strain on an instrument that may well not have been designed with steel strings in mind. YMMV.
If you've got "larger" hands you might want to consider a concert sized instrument, for that little bit more finger room, if budget permits. For the purposes of quiet practice, should circumstances require, or even a change in tone for folk music or such, an easily removable resonator might be advantageous
Pretty much any of them, but I find my concert size easier to play than my 6" soprano. My concert is a Rally (same as Eddie Finn) and both are in reality Goldtone clones. I prefer the full resonator on it and it has a calfskin head (Remo Renaissance would work great too). I feel these two heads sound more "banjo like" I could never have lived with the mylar head it came with. Nice clawhammer tutorial provided by Aaron Keim. Lots of banjo ukers here.
I was playing my Firefly with a group of old-time players a couple of years back at the Dance Flurry Festival in Saratoga Springs, NY. About one to 1-1/2 hours in, someone noticed that I was playing a banjo uke, not a banjo.
One thing I forgot to mention is if you get one with a resonator back get a strap, because they are heavy compared to a standard uke. I could not play one for long even sitting down without a strap helping. If you go with an open back like the Firefly you won't need a strap. I played a Firefly recently and it was very light, but definitely not as loud as the Eddy Finn.
I have an old Slingerland MayBell soprano (open back) and a Eddy Finn concert (with resonator and WeatherKing Remo banjo head) and the concert sounds waaaay more banjo-y. EF is excellent quality and bang for the buck.
Good luck with clawhammer. I tried getting the hang of that - then crawled back under my rock to lick my wounds.
I just noticed this is your first post - welcome aboard!
I'm currently tossing up between ukeifying a tenor banjo or trading said banjo (at quite a loss) for a Uke Banjo, probably a Gold Tone or maybe a Pilgrim.