Choosing a power supply

I have a question, which power supply would be better to get?

I'm looking at a RM 650 or the new XTR 550w(Link). They are both similarly priced at £80

They are both gold and both seems good. But I was wondering if I should get a XTR because of the Seasonic platform of the G550.

What are your thoughts? If you have other suggestions, please state them.

 

I don't have much experience with XFX PSUs but I have heard good things. 

I have had plenty of experience with corsair PSUs though, and have just used an RM550 in a mITX build I did. It has been fabulous so far. Excellent build quality, love the modular design and it is so incredibly quiet. I can definitely vouch for an RM series PSU.

http://www.eggxpert.com/forums/thread/323050.aspx

That link is old but it splits up the PSUs into tiers. Separates the makes/models in terms of quality.Maybe this could help.

Do you want it to be modular?

Because if not, I recommend the S12G-550 (or 650): http://anandtech.com/show/7761/seasonic-s12g-650w-power-supply-review. It should be cheaper than the other options (in my country it is).