Go with any Google phone, they're developer friendly, support jailbreaking without doing anything crazy, has good upgrade path, and supported by 3rd party mods

Go with any Google phone, they're developer friendly, support jailbreaking without doing anything crazy, has good upgrade path, and supported by 3rd party mods like cyanogenmod. All the other phones are basically crap -- you'll get one upgrade option if you're lucky, and it probably won't get 3rd party mod support. My Nexus S can get up to jellybean even though it started from gingerbread. I suspect the future Google phones would have a similar level support. I also owned the nexus one, but sad that it wouldn't go past gingerbread.