I would choose the non H2AD engine airplane every time. Yes, some are better now, but when they go bad, they go bad bad fast, and you're headed directly for expensive maintenance. You'll budget the overhaul cost into the hourly operating cost of the plane. Hopefully, you can convince the authority to allow you to operate the engine (in private operations) beyond recommended TBO. (it is only a recommendtion, not a hard limiting time). There is enough international success with this, that there is a good basis to ask for the privilage, with the international guidance material to support continued airworthiness.
Bear in mind (though I'll be tromped on for saying it), quality, non "oxygenated" Mogas is probably a better gasoline for that engine than Avgas. Avgas is a horrible compromise for the low compression aircraft engines, so the high compression aircraft engines could have a fuel, while to producers only had to make one product. If you can get good quality Mogas, that's what you should use in a Mogas STC'd Cessna. Be sure, that if you are using it with a Mogas STC, the Mogas you get meets the quality requirements of that STC. That might not be quite as simple as it might sound in some parts of the world.