Anything by Estes. If you mean the kind that actually launch. But honestly, it’s not that hard to make a rocketry kit ‘good’. They are basically like paper towel roles, only thicker cardboard, with balsa wood fins, a plastic nosecone, a mounting for a gunpowder engine and a parachute stapled or glued to the inside.
Basically for their first rockets, I’d avoid any multi-stage rocket kits. Get them single stage. Basically the difference is that the multi-stage have a charge that shoots up to ignite another engine whereas the charge on a single-stage engine is concussive in order to force the parachute out. The multi-stage rockets are harder to do, and they can often change trajectory by having the engines light improperly. Having a three stage rocket go horizontal is not uncommon. But if you do it right, they fly really high.
This one looks good and simple.
Remember though that the rocket doesn’t come with the launch pad and such. Though you could probably find a kit that does.
I always liked the models of the missiles when I was a kid. It looks like they’ve discontinued my favorite one, but this one is similar.
What separates the ‘skill level’ is essentially that it has more fins. More fins means the alignment has to be more precised. Also there are different powers of engines.