I've installed and tested about 6 different UI's from the conanmods site. The two I've found most compatible with my play style were Mirage and the AnarchY ones. I had some problems with installs a couple of times, but usually, downloading the latest version, deleting the customized and default folders and putting the new ones in their place fixes everything. Yes, you end up having to redownload the latest patch version during your first login with the new UI, but they both work fine for me.
I'm currently using the latest Mirage because it has 99% of the features I'm looking for and NONE of the others hit 100% either.. but some come as close.
Best suggestion I have is to download various ones and try them. You'll only know after playing with each a bit, which one you like best.