If you have a phone that you could manage to get by with for another few weeks, I'd wait for the Nexus 4.<p>If you really can't wait, there are still some good options. The S III is one of the best phones ever made. The Note II is just as nice as the Nexus 4 and the S III, but it might be too big for some people, myself included. Also, you might be able to find the Galaxy Nexus, which is the phone I currently use. The Google version is no longer for sale, but you might be able to find a brand new one on Ebay, or if you aren't comfortable with that, some of the wireless carriers might still be selling them.
A Samsung Galaxy S III with Cyanogenmod 10, which is usable as a daily driver<p>- or -<p>If I could deal with the size and pending a usable CM10 build for it, a Galaxy Note II, which is essentially a giant-screened SGS III with monstrous battery life and a pen (which won't be usable under CM10).<p>Both support 64GB microSD cards, unlike the N4.
Wait for the Nexus 4. I've had one stock Android phone (Nexus S 4G) and 6 non-stock. Stock beats custom skins, hands down. I know CM is (mostly) always an option, but the hassle is reminiscent of trying to remove bloatware from a Windows PC.
Wait till it's back in stock -- as a developer you want to be seeing the flagship model and Nexus is it. And I say this to you as an Apple fanboy who just ordered a Nexus to make sure I know what's going on in the other side of mobile.