Man I'm ripping up a lot of floors these months! I'm dealing with an incredibly uneven subfloor right now. Used to be carpet. Previous owner filled the most egregious valleys with floor leveling compound that's old and turning into dust. So i need to decide the following:

How to fix it? And then what to put down - laminate or vinyl plank?

So I can either hire someone to just put big sheets of plywood down across the entire floor. Generally speaking, if i do this, I won't need to otherwise correct the flooring right?

Or, I could grab my planer, my belt sander, and some levelling compound and do my best to level it out a bit.

In terms for flooring, I'm either doing cheap laminate or cheap ish LVP (it's a rental). The laminate is a bit more forgiving because i have an underlayment but for the vinyl plank if i remember correctly the floor has to be perfectly flat because you don't use an underlayment. The kind i used has sticky edges and you just stuck the edge of one piece to the edge of another.

I loved how easy the LVP was. I didn't need a saw! I'm terrible at a jig saw so even though I've done laminate before it's frustrating and any detailed areas don't look so great.

If i hire someone to put sheets of plywood down, do i still need to use floor leveler? If I use laminate, could I get away with planing down the worst peaks but leaving a bit of unevenness and getting a thick underlayment?