It said yes but asked me to choose the AT&T kit or T-Mobile kit. So, my first question is: Which one?
And the answer, as always in choosing a carrier, is which one gives you the best coverage in the places in which you need coverage? Secondly, which radios does your phone have, and which carrier's high-speed frequencies do they match. Sometimes the carrier you need and the phone you have aren't compatible - and the proper solution to that is to sell the phone and get one that will work for you.
Second, I emailed the company selling these kits and asked, and they said no. It was not Net10 but said that they are official carriers of Net10. They're called "Quality One Wireless, LLC." So my second question is: Are they authentic?
Don't know and, even if they were the most honest company in the world, wouldn't care. You can buy the kits on Net10's site, and I KNOW that's authentic.
And lastly, if you know that Net10 won't work, can you recommend a prepaid carrier
Net10 is an mvno - a mobile virtual network operator - not a carrier. They have no equipment, they put you on the towers of, in Net10's case, the big 4 carriers. If it's an unlocked GSM phone, it'll work on TMobile or AT&T. Net10 and Straight Talk are the same company (American Movil), offering the same product (access to TMobile's or AT&T's network) just at different prices. Any other mvno that offers access to TMobile or AT&T is going to work also. It's the phone and the carrier that determine whether it will work. (Of course if it's "Joe's Cellphone Company" and he goes out of business, you're out of luck, but American Movil is owned by one of the wealthiest men in the world, and it's here to stay.)