I've wanted to try the Kowa for a number of years now but they can't be found in town, so I've made many mental notes from everyone's posts here. There doesn't appear to be a consensus on this one. Some will say the Kowa is better and some will say the Zeiss is better. I have the Zeiss so I am familiar with it and I am content with it and I can live with its shortcomings and appreciate its strengths. Optically, the Kowa side of the debate contends a little bit sharper on axis and a little less CA off axis. I've seen infrequent and brief price reduction on the Kowa at just under a grand which puts it more in line with the Zeiss, but it may take a year for this to come around. Go to Allbinos.com and check out the allbinos rankings of 8x32mm glass, both have been reviewed and you can decide which criteria are important to you. Also, you should demo the Maven and then you will know and only be out a few bucks for the postage. It is a bit of a different package than the x32 Zeiss and Kowa which may or may not appeal to you, and offers reasonably good optics.
Four that I have on hand at the moment; Leica 7x42 UVHD+, Swarovski CL 8x30 (2018 release), Zeiss Conquest HD 8x32, and Maven B3 8x30. If I was going to cut this group back to two, I would keep the Leica and the Maven as that is what fits my needs and uses the best. If I was to cut it back to just one, ???? I don't think I could make that decision.
My .02,
CG