Which one is better best movesets or best ivs?

Move set. No discussion possible.

Move set, hands down!
However...
Today you can change move set with TMs, but you are, at least at the moment stuck with a bad IV.

IV also plays lesser and lesser role the higher stats the Pokemon got.

15 + 300 (like Mewtwo) is much less significant than
15 + 29 (like Magikarp)

Perfect IV is mostly a collector item, not really of practical importance.

Moveset is more important to battling.

IVs are more important overall.

This is because Moves can be changed through a rare reward from Raids.

Having the best charge move is great, because you can get unlucky with TM tries. The fast move is simple to get.

IVs because they are forever, you can always TM the moves to get the best one

Depend on your opponent. If you want to use a Gengar against a Confusion Alakazam, you want a 100% IV one with SP/ShB, but definitely not the one with 0% IV, but with SC/ShB. The DPS difference does not make up the bulk that it loses. However, you want to solo a Ninetales, you definitely want a Gyarados with Waterfall/HP with mediocre IVs, but probably not the one with Bite/Twister with 100% IV.

Moveset is only important only on high level usable Pokemon. However who really wants to invest dust and/or TMs on crappy IVs?

IMO both are equally important, that's why we aim to have the best IV and Moveset combined. Especially once you obtain multiple evolved forms.

Don’t higher IV’s result in higher CP’s?