Okay,
“Checkout 2” and “Cart 3” are by @yuzool and if you haven’t been paying attention he has zero support and has left the RW community other than selling products and collecting money.
“Stiva” - I never heard of them so can’t comment.
“Cartloom” - is a good option but there is a monthly fee.
“RapidCart Pro” Is a very flexible choice, onetime purchase, but with flexibility comes a bit of complexity in the setup process.
“Paysnap 3” is simple to set up and might fit what you are looking for. Depending on what you are selling and options etc. Might check out the demos. and see if the options look flexible enough for you.
And you didn’t mention it, but there’s Ecwid both a free plugin andpaid stacks. It has a monthly charge but there is a free plan that can be used for I think for up to 10 products.