Hi MacIsaac
I gotta say I am not a fan of hand tats but whilst I have been researching for my book I have seen many.
The one font I would definitley give a miss is old(e) english – it stretches and blurs a lot from the pics I have seen (I am not an artist just going on what I have looked at). I think it is because the skin stretches across the knuckle region.
One font I have seen that looks fairly crisp is Tahoma – you can see it on word docs.
If you are tattooing just below the knuckle then pretty much any font would remain clear as the skin does not move much.
Anyhow good luck with it.
Matthew