Never been a fan of USOs I like the idea but glass and reliability were not their #1.
S&B I had 5, 4 - 5X25 PMll and one 4X16PMll. Glass is awesome. Was able to see bullet holes in the target at 600 yards, so resolution was phenomenal. H2CMR is a very useful reticle and one of my favorites for movers. All that said they had a few issues. Zero would drift a few 1/10th. So I dumped them.
Kahles was a sponsor of the team I was shooting for. So had them for for a while, well the glass would do some crazy things in certain light. Bullet impact would change with a magnification increase/decrease. It took a while to figure this one out. Luckily I have a good partner and we push one another. He challenged me to shoot a 500 yard target at 15X that was an impact then went to 24X miss 3 times. Adjusted parallax and tried again impact moved back to 15X and miss again. So they all came off.
Now from the best of my knowledge both companies have improved QC and these issues have been resolved.
Hensoldt that has the best glass hands down. The model was a 4X16, turrets were a little hard and hard on the fingers due to the shapes of the turrets. When the 3.5X28 was first offered, I was on the preorder list @ 4k got the call that they were in, price increased to 7.5k. I declined the order. At 4k I was in, at close to 8k I could not justify it. Maybe one day I will nut up but I have other things I would rather have.
Vortex Gen ll, It tends to be my go to. You can dead nut zero. They are built like a tank and weigh as much as one too. I usually pick them up used for 1600-1700. The glass doesn't have the resolution of the 3 above but it holds zero no questions about
Premier Heritage is another example of very good glass. Unfortunately it would drift zero took a 6 day long range course and every day I had a re zero.
TT I believe bought them out, I never bought one the few I have looked through very nice glass. I can not comment on reliability.
ZT only looked, nice glass they are supposed to be bomb proof. I can not comment. Again for the money I spend it on 2- Gen ll for the one ZT.
That's the long answer to your question, if you have the flow it's worth it. If it's a little tight Gen ll or NX8 will get you on target and keep you there for 1/2 the price.