I think you will find this is going to be largely a matter of opinion. I recently went through the same debate with my new setup. It is kind of like comparing Chevy and Ford.
I went with the AI over the Kessil. I decided this for two reasons. First I was going to need 2 x A360x with a controller to cover my tank or I could get 1 x AI hydra 52. I did some research and like how I can control the AI through my phone without the need for an extra controller. Plus, I saved money by only needing 1 AI vs 2 Kessil.
If you use the R2R search function and enter "Kessil vs. AI Prime" then you should find several related threads. What are you planning to use the light(s) for (e.g., depth of tank, width of needed coverage, reef/FOWLR, etc.)? Do you have a specific Kessil in mind? Good luck!
I have an AI prime on my 40 gallon innovative marine cube tank. Honestly, I have been pretty happy with it. But I was talking to a gentleman today that felt as if they are prime had hotspots therefore burning some corals. And he felt that maybe the Kessil had a better overall light with a truer color. Maybe it is how I have my Ai Prime set? And then again – like I said I have not had any problems, I was just curious to see what the general consensus was out there.
I’ve seen corals look really good under AP700s... I do like Kessil shimmer, so between the two? I’d maybe go Kessil, although I don’t experience with either myself, just based on seeing people’s tanks with my own eyes.