Okay, I was a bit unsure with this phone. After settling on it, and finally getting it - I, again, was unsure. I could have gotten the G3 which is much newer and has a lot of better features. The camera is quite nice. But, spec wise, they really are not that different. A bit here and there, but it's not like comparing the evo to the nexus, its more like the evo to the photon or something. I never looked into that phone too much myself... >.>
Okay, so I've now rooted my phone, sitting here with CM10 on it, stock kernel still, and sure it's awesome. It's an excellent device, that being said the G3 is still something I think about from time to time. Mainly because at the time, the evo was the top of the line phone. The Nexus is not top of the line right now. Probably the g3 is. That's fine though, look who's rocking JB.
I guess what I'm trying to say is that if it comes down to these two phones, you win. The nexus is great. I love it. I'm always playing with it, just like when I got the evo initially. The G3 will be more current for a longer time, but no phone lasts forever. I think the nexus will be fine for quite a while. In all honesty, the evo would be fine for some time yet.
I apologize- this isn't my best worded post (but probably my longest) so I want to sum it up a bit... The nexus is great. Rooting it is easy. I think two commands, maybe three. The hardest part for me was dealing with MTP - which for many won't be an issue. I know it sounds a bit negative at times, but it shouldn't. I'm trying to be honest and objective. I still think this phone is awesome. And with ICS/JB, you have a very modern device. Just know that it isn't the 'best' on the market. But, if you are looking for an AOSP phone, this is clearly it.