Every Android phone is a Google phone.. it's powered by a Google operating system. But only the Nexus line provide the full Google experience (which isn't much more than random Google Apps you can download on the Market.) Anyway, I vote for the Sensation. Get it.
HTC sense is sexy as hell, I haven't seen a laggy HTC device in a while. Even the droid eris isn't laggy and that phone had a 528mhz processor, with 288mb of ram.
Wut? Then how come my Inspire was terrible on its stock ROM and so was my friend's Evo. Maybe I'm too sensitive.
Maybe, lol. I mean for me, going from iOS to android is always hard. HTC sense compared to Motoblur or Touchwiz is amazing IMO. Don't get me wrong, nothing is as smooth as iOS.
Nexus S. Get your updates, fun and easy to hack. Stock out of the box. When given the choice (and you have to go Android...) go Nexus.
Between the Nexus and HTC, I'd go with the Sensation. But personally, I'd get the Galaxy S II. And my second choice would be the Droid 3.
...but Droid 3 won't do any good because that's Verizon only and he's looking for a T-Mobile 4G phone.