The Kocevlo and Ullicyc are the same bar and they are both copies of The One Pro with a different clamp design, but the stem and bars are the same. I bought both The One Pro and Kocevlo bars and they are identical apart from the steerer clamp. The One Pro were about 25g lighter (370g vs 395g); whether that's the clamp design (likely) or a different carbon layup, I couldn't tell any difference between the two. In the end, I went with the Kocevlo due to being half the price. They've been on my bike since May (you can search my posts) and I've raced them a dozen times or so. I like them and would buy again. They're plenty stiff for me and I'm around 85kg and can put out 1600W peak in a sprint. No flex I can feel. Finish is on par for AliEx bars and I don't have any safety concerns even at my weight. I ran mech 1x and now Di2, no issues with cable routing apart from the usual annoyances of fully internal bars. Couldn't tell you if they could handle 2x mech but they look to have ample room albeit a little tight.

So the consensus seems to be, that the Kocevlo bars are the way to go. Would you rate the stiffness on the same level vs The One? The 25g weight difference would be totally worth it if the build quality is the same overall.