I think a good question is, why do you feel UC is not working for you. What pads are you using with it? Are you working the UC long enough? Perhaps the problem is not the compound but rather something else. I'm guessing that you are using a DA? If so, what kind? Again, I think the _real_ question to get you a better answer is knowing what you feel is lacking from UC.
Personally, UC is about the only aggressive compound I use. Compared to M105, I'll choose UC any day of the week. M105 just dusts _WAY_ too much for me. UC is just slightly less aggressive then M105. For heavier work I'll go with an orange pad and UC. For light corrective work I might switch to a white pad and UC. That covers a lot of what I'd be doing. UC can be worked as long as it has not flashed and it takes awhile to do that. One thing that I do and I'm not saying it actually makes any difference but I'll lighten up pressure to almost nothing on the last pass or two of a section. I can't say that I actually see a difference but I've worked it into being a habit. If I'm looking for a more mirror like finish (2 step polish) I will then go with something less aggressive.
I know a lot of people on this forum don't mention using UC. Perhaps it is because it is an inexpensive item that can be bought locally. But I'd not underrate it for that reason. Typing this, I just thought of something. Someone should create a video where they take a few products, put then in nondescript containers and then have someone else use and rate them. There are _so many_ video's giving reviews of product and comparing them against each other but in all cases, those brands are known. Putting them in non descript containers would remove all bias. Course, I think then we might see that most of these products are really about the same.
For a 2nd step I'm now using Menzerna 3500 or 3800. I like it for the same reason I like UC, I can work for a long time as it does not flash out quickly. But it is really subjective.
I think you may want to look more at ways you are using and applying your compound but of course, you need to feel good about the product.