Hey Gerard, So you are planning to root down your device to enjoy custom skins out ...
, okay coming back to your question every custom ROM has their own features and advantages, which means for me both of the ROM you have opted is good to go with
I don't have the idea about Evervolv but I have used CM11 personally. So I know going forward with it's much more preferred.
If i talk about disadvantages then I would say sometimes custom ROM may posses unseen bugs which results in poor battery, performance etc.. so its often said to remain with stock ROM, another major disadvantage I can thought of is the flashing custom ROM requires rooting your device and rootin the device means your warranty gets void
So, I would say you better not to do that if you have purchased the device recently and have an active warranty.
But if you what you're upto then go ahead try custom ROM out they are way more cool than stock ROM my vote goes for CM11. 
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