I agree with those who say ideally .domains if you have a great word that goes with that.
That being said, I think loads of other extensions would work well if there is a sensible match of word + extension. While some like .shop, .store,.market, .world, .global, might seem more obvious, I think even many others could work well.
I think it depends somewhat on the type of domain operation you foresee. The tone of your name should match the brand of your store. Is it mainly business end users, of a serious bent? Or mainly startups that might be more adventuresome? Creatives that like something a little risky? Or a lot of NGOs that don't really like a commercial tone?
Is it strictly domain sales, or more generally a service re branding, protection, technical help, etc. If the latter, I might shy away from .market, .shop and .store that would box you in a bit.
Strictly English language, or more global? I know .xyz does not get much love on NPs, but the fact that it is not language specific has certain advantages if not strictly English end user clients.
What extensions do you see yourself mainly selling? I see some benefit in modelling what you want to sell to others, so for example if you plan to handle a lot of .online I might choose that (or similarly with .store, .shop, .world, etc.).
Best wishes for success.
Bob