Really the best thing to do is try them. Personally I'm a fan of Boxed UI, it's a very clean and very smooth looking UI. The others I find to be very cluttered and trying too hard to be 'cool' looking by packing on as much stuff as they can think of.
Boxed has a few different color schemes, but I prefer the original, it's not too dark and it's not too light... it's just right.
Boxed r74http://www.vgsohinterface.com/downloads.php?do=file&id=16Boxed Silver r74http://www.vgsohinterface.com/downloads.php?do=file&id=36Boxed Darker r74http://www.vgsohinterface.com/downloads.php?do=file&id=31Also, keep an eye out, I spend part of my time this weekend folding a couple of different side mods into Boxed, including JournalMod from Drox and TreeviewColor. I'm currently working on getting the EV map in without destroying Boxed's windows frames around the map. Once I have this all complete, I will release a compilation. Screenshots coming soon
