I'm playing with upmind right now. So far my impressions are that it takes more clicks to do things and at least on domains, it just seems weird that the tld is a separate field. I like the UI and feel, but otherwise, feels like it takes so much more work to get provisioning going. As someone in another thread mentioned, their logic seems illogical.
I'm also looking at hostbill because it can provision Rackspace email. Not a fan of the pricing model.
Clientexec UI seemed meh.
Fossbilling also looked meh and doesn't to seem to be that active of late?