I agree that it's all down to personal preference and the best way to find the right one for you is to try and few and see which you prefer. Although it's important to take the time to set them up and get used to them before making a decision. There's been many addons where my first reaction is it's totally wrong for me, then once I've gone through the settings it looks far better.
There's also the option of using a few more specialist addons instead of one big one. I use Votan's minimap, S'rendarr for buffs and Azurah for other changes because I prefer the end result to any of the combined UI addons and it lets me pick the features I want and skip ones I'm not interested in.