We always preheat to high temperature, my kids have been really like Kroger brand frozen pizza lately. They are not great but not Freshetta bad either.
I’ve tried most of them and they’re mostly too bland for me.
The only one I find somewhat satisfactory is actually one of the cheaper brands - Jacks. I buy the thin pepperoni and pull the meat off, add a bit of extra cheese then the pepperoni goes back on with a bit of chopped onion.
Their sauce actually has some TASTE. To me the most important flavor ingredient after the toppings is the sauce. I find most people like very little sauce. I like a generous amount.