I'm gonna get flamed for this, but I have loved my 10x50 UHD's. I picked them up last fall and couldn't be happier. I ran the Maven C.1's prior to them for a couple seasons, and was largely happy with them. Then I got the UHD's, and the first morning I had them, my buddy and I were up scouting for mule deer. We both set up our tripods and mounted the binos. My buddy looked through his Viper's, and said to me "Well, it's too dark to see anything, I'm gonna make breakfast." I responded with "What are you talking about? There's a doe on the bench below us at like 900." He didn't believe me, so I handed him my UHD's and I tried his Viper's. His exact words were "Holy $h!t you're not kidding..." He passed them back to me and we spent the next 30 minutes with me comfortably glassing and him straining to see easily through his Viper's. My old Maven's were basically even with his Viper's, and I gained a legitimate 30 minutes in the morning glassing, and I've been more than happy with them.
I've compared them side by side with Swaro's, and I can't stand the "greenish" hue that Swaro casts across the view. It messes with my head. Edge to edge was comparable to the SLC's, and I didn't even really see a difference with the EL's. The NL's were better slightly edge to edge and had a wider FOV, but their ergos SUCKED.
The Zeiss is closer for me, but the Zeiss I've used look almost yellow to me, which really sucks in late season when there's snow on the ground.
Leica's are the only thing I've looked through that are better, but they're also significantly more money. If I ever upgrade, I'll go to a Leica. But until I've got an extra $3k laying around, I'll be happy with my UHD's and I'm not looking to upgrade or replace them any time soon!
Like I said, I'll get flamed for my opinions, but I've been very happy with them.
But hey, I'm just some random guy on the internet...