I briefly had a Nexus 4 and quickly returned it. It's noticeably cheaper built than the others on this list, and it has horrible battery life and voice quality. I found the Nexus 4 inferior to the S3 I'm currently using, and even the iPhone4S I had before.
It's been very good to me so far.
Depending on what turns you on, in a comparison between this and the iphone the nexus cost £250, does everything the iphone does as well if not better and does more. The iphone is £700, does less, is the worst actual phone of the bunch and ties you into Apple's bullshit.
I'd say the Samsungs are probably good to but I've not had one of those.