So i'd really like to upgrade and am trying to figure out what to get. (Coincidentally it seems that +Wil Wheaton is pondering almost the exact same question today.) For me i think the top contenders are the Galaxy Nexus and the Galaxy S3. The HTC One X is probably a somewhat distant third choice.
There are some reviews comparing the specs on the Galaxy Nexus and the S3 (and some comparing the S3 and One X as well.)
So let's do the pros and cons, at least as i've figured out so far.
Galaxy S3 Pros: It's got a 1.4 GHz quad-core processor (compared to 1.2 GHz dual-gore on GN) It's got Gorilla Glass 2, which from what i understand is better than the "fortified glass" used in the GN. It's got a slightly better battery than the GN. It has a menu button! Google is trying to kill the menu button in Ice Cream Sandwich and i hate them for it! I love the menu button!
Galaxy Nexus Pros: It's got stock android. So there's no stupid "TouchWiz" to work around and it will get OS updates much faster. It's available unlocked directly from Google for $400. I can just swap sim cards and keep my same (relatively) low cost no-contract plan.
Galaxy S3 Cons: It's only available in blue or white. What the hell? It's not actually out yet. It comes out at the end of the month in Europe and who knows when in the US. If i want to get the unlocked version the current guess is that it will cost about $700.
Galaxy Nexus Cons: There's no SD card slot, which is bad. And since i'm on T-Mobile i'd have to get the 16GB version instead of the 32GB version. Even worse, someone decided the headphone jack should go on the _bottom_ of the phone. I have to stick the phone in my pocket upside down? I can't rest the bottom edge on anything if i'm listening to music? That just seems incredibly awkward. The camera apparently sucks. I don't care about the 8 megapixel vs 5 megapixel thing, but apparently the GN camera takes rather washed out pictures and is really poor in low light conditions.
Cons for both: They both are using "PenTile" displays rather than RGB. This is apparently... bad? I dunno, i don't usually stress out that much about graphics so who knows if i'd notice or not. The shell is also made out of some kind of plastic. I really like the sturdy feel of my N1 with the metal shell. Neither one has a trackball. The trackball in the N1 is awesome.
Also, they're both rather large, and i'm not sure if that's a pro or a con. It's obviously good for looking at stuff on the screen, but i'm not sure how easy they are to hold, and i don't know how well they'd fit in my pocket.
So if you just add things up by "number of pros and cons" it looks like the Galaxy S3 comes out significantly ahead. However stock android for the GN is a pretty fricking big deal, as is the stupid colors for the GS3. In fact, between the two different versions there's a frickin lots of cons stacked up.
If only i could have a phone in a nice color with an SD card slot, the headphone jack in a reasonable place, a decent camera and stock android. I suppose if they eventually add more colors for the GS3 i could get one, root it, and install Cyanogen?
You know what, as a functional device my N1 is still perfectly, well, functional. It makes calls, it tells time, i can listen to Audible, i can record workouts i can browse the web (as long as i don't mind 2G speeds away from home) and read email and check in to Foursquare and GetGlue. There's supposedly going to be a Google Nexus Tablet out in a few months, maybe i should just get one of those (or if that falls through, an Asus Transformer) and use that for trying out games and other cool new apps? Then in about six or seven months i can see what the next Nexus phone will be.