I just switched over to Verizon from AT&T this past weekend. Not the best timing with iPhone 5 in October(ish), Galaxy S3 some time soon, etc., but I can only assume I'll just pay full price for a phone later in the year.
When I switched over, the Nexus had caught my eye. I've had an iPhone since the original, and it was/is getting a bit old/boring. The Nexus had a bigger screen, completely customizable and just looked absolutely beautiful. With ICS involved, I wanted to give it a go. It's Wednesday, and I'm back on an iPhone.
The Nexus software is awesome. There are literally limitless possibilities on customizing this phone for yourself with widgets, live wallpaper and the App drawer. With the iPhone... change your wallpaper if you want to customize. I chose the Nexus just because it was considered the "Vanilla" ICS, and Verizon/Samsung didn't bloat down the OS with additional stuff.
However, the radio antenna was absolutely horrible. I never had a signal when I was in a building, and this is my PHONE. This thing makes an unbelievable pocket computer, but when I require a phone for work and this thing can't make a phone call, it's useless to me.
Long story short, wait for the SGS3 if you can and see what it has to offer. I'm going to look at the SGS3, the iPhone 5 and the next Nexus and see what they have to offer when they come out.