best iPhone6 Model - US and UK

https://www.apple.com/iphone/LTE/

Is it better to purchase the iPhone in the US or in the UK for best compatability for networks? I'm in the UK until Nov. 14th, returning to the US until January, and then I may be living here for a year then. I want a phone that can work best in both countries, but I'm not sure if the 1st set of phones will be best (A1549 / A1522) or the 2nd (A1586 / A1524).

It seems that the main difference is the 2nd set offers support in the TD LTE Bands - but does that mean that it can support the other networks (ATT/Verizon) as well, or no? I'm confused by what is meant by the carriers listed beside the versions when a lot of the same bands are covered.

 

From my research, I really think any of them will work for US/UK - so long as you can get it unlocked, from what I know there's only 2 different models of each size, and the only difference is on supports more bands used in Asia, but the US and UK ones are there in each.

I've order Model A1586 here in the UK and get it early October, but I won't really know if there's limitations until I'm back in the US (Mid November), and back in the UK for a long period of time where I'll get a UK contact (January I believe).

I believe you're good no matter what - though if you can buy unlocked in the US it will be cheaper.