Unlocked phone recommendation

My iPhone 4 has slowed to a crawl and I was wondering what the good options for a an new phone. I'm looking at the Moto X or Nexus 5, but those have been out for a while and was wondering if there was anything out there for around $300 that is better. I'm not interested in the Oneplus One. Thanks.

I have a nexus 5 and it is a great phone. Super fast and the camera is good. It is also a good phone. You can run other OSs/ROMs with ease too. 

Oppo makes unlocked phones too and I have heard they nice.

+1 on on Nexus 5

Thanks for the recommendations guys.

It looks like Motorola is about to release an update to the Moto X in a few weeks. So I think I'll hold off purchasing till then to see what how it looks and if prices drop.

https://news.yahoo.com/leaked-moto-x-1-front-panel-shown-side-003025357.html