Back to the original question: I just gave the new Windows Live Mail a try, and found that it handles IMAP-enabled gmail accounts pretty well. So you might want to try that.
I’ve been using the free version of Postbox for a while and have been fairly happy with it. I don’t believe it is being actively developed or supported anymore though:
Paid version of Postbox
Been meaning to try Pegasus and The Bat, but haven’t got around to it. I found Outlook and Thunderbird to be really unresponsive with IMAP.
Anyone on OSX (or considering it) should also check out Sparrow. It’s a GMail-centric mail client (although other account types are also supported) and is very good.
I’ve tried Postbox. It’s basically a more attractive thunderbird fork. The newest version does support outlook-style multiline vertical subject lists, which are a huge usability enhancement, but performance is pretty terrible. I played with the trial but didn’t buy it.
I’m also using this for my hotmail accounts. Works good enough for me. Quite lean.
Sigh, okay, thanks for all the suggestions in here guys. I tried Thunderbird, Postbox, iScribe, Windows Live Mail, The Bat, Eudora and also tried doing that forwarding gmail thingy and a few others I’m forgetting the names of.
Sadly, I hate to admit, none of them worked to my liking (Windows Live Mail was the closest, but damn is that program problematic). So…I’ve returned to Opera. It just does everything I need so cleanly, there sadly isn’t any contest, though I was so hoping there would be one.
Thanks again for all the suggestions y’all. :)
It won’t hit Brian’s requirements, but on OSX I’ve been using Mailplane ever since we went to Google Apps for work and it’s quite good AND supports multiple accounts well. It’s not cheap though, but there is a non-crippled trial.
Yeah, honestly Mac looks to have some damned sweet email clients. Shame that can’t be said on the PC side.
Arise!
So I just reformatted my PC and reinstalled Windows, and rather than go through Opera again, I’ve stuck with Chrome, so in striving to find a new email client with unified inboxes and gmail support, I found EmailTray. It’s pretty nifty. It immediately detected both my gmail and google apps mail accounts, and went through sorting them by priority, which I can change easily, so now I go through all my email pretty quickly. I’m really liking it so far. :)