In an earlier post I mentioned the way to reeve the blocks so they don’t twist under both load and no load. It works. But you MUST reeve them correctly.
https://www.harken.com/content.aspx?id=3901
The rule of thumb for blocks is: The larger the sheave diameter is proportional to the lessened friction. And the better quality blocks with better bearings. Sorry. Can’t help with which is quality and which is not.
It’s been 20 years since I had to buy blocks. But definitely Don’t get ones with delrin or nylon bearings. Stainless or bronze bearing/bushing only.