Wayne- I am not sure what I am going to do, but I want to do something. The CH750 has me concerned as I have watched too many skins wobble in the prob wash. I feel it would be a great starter plane, but afraid of resale value. IMHO Any VANs hands down are far superior to anything out there, but you will spend a life time crafting them. So the RV12 is the only one I would do. The S21 Rans is looking very good to me, with a kitfox second.
Hi!
We have a Zenith Cruzer that we built here at 1C5, and the one I'm building is almost done - you'll see an update post in a moment. They are very nice little planes, roomy, great visibility - like a kind of modern, chubby, Cessna 150. I have about 40 hours in them and the only oil canning I have witnessed is as a kind of stall or "out of coordination"warning.We say she is talking to us and letting us know what's happening to the air - works great as a reminder LOL.
The RV12 is a lovely little bird - my friend has a great one. He is now building the Rans 21 and it is going together fast. The RV 12 is like a swiss watch compared to the first Zenith we built which is powered by a new Continental O200 D with just headers. So manly and American. We love it! Of course the Rotax 912 is quieter and not as brutish

The Rotax and Continental swing nice long props - but for my Cruzer I'm using the UL Power which swings a shorter prop as it gets it's power at higher RPMS so they have to watch for tip speed. Draggy airplanes do better with longer props is my understanding.
If you stay in the 100 HP area, and you are going Light Sport or have a draggy airplane, the Rotax is a superb option. If you want air cooled and direct drive then you have the traditional engines or the UL Power. THe UL is full fadec, lightish (176 pounds installed) and modern. It has some downsides though - needs MoGas as it hates lead, and mine needs 93 Octane. It is also newer so less sample size for issues. US support has been very good for me, and they do a nice job of posting service bulletins. Don't forget though, that I have yet to fly behind mine although I'm closing in on that date.
I know there are a bunch of other options (D-Motor / AeroMomentum / many others) but if you want a more or less plug and play experience you will go with the firewall forward recommendation from the manufacturer so you can buy the FWF kits and trade money for time.
One other thing that might make a big difference is the familiarity of your local resources with engine type. Some areas have very little or zero engine knowledge outside the incumbents so that might be an issue if you are not comfortable servicing your own motor.
Final point - if you are going light sport with some designs like Zenith who give you many options for power don't forget weight. Just because Zenith say's you can put any motor in as long as it's less than 350 pounds (I might be off on the weight) does not mean that's a good idea given the current light sport max gross of 1320 pounds.