Re: engine manufacture not sure what to get
I take it from your list of possibilities that you are not in the USA. It's going to depend on what boat you purchase, really, and having a servicing dealer for the brand you choose. Otherwise, they're all good.
Pick an outboard that has the horsepower rating suggested for your inflatable, then choose one that has dealer service available to you locally. 2 or 4 stroke isn't really an issue, frankly. All the new motors will run just fine.