having never had a GPS problem with my X I'd assume you have a lemon. whatever phone you decide to upgrade to, I'd recommend that if you get a weird problem like that again, simply take it back to swap for another. lemons happen sometimes.
that said, I don't know of GPS differences between phones for you to upgrade to, but the galaxy SIII is about to come out, and should be a beast of a phone. and of course, the droid razor maxx has amazing battery, though personally I won't be buying another motorola product until they stop locking bootloaders. also the HTC one phones and the huawei ascend d look like pretty amazing devices, and should all have good battery since they have some pretty nifty processors.