If you can truthfully vote for 10 different skimmers, I would think research was lacking on what should be a very important selection for your system. Up to a point this is a financial decision especially if you are running a large system. A top performing skimmer for a 300 is a budget breaker in excess of $1000 yet you can get one that will work ok for much less. Is ok good on a reef with $10k in livestock? Not for me.
Like anyone I got what i could afford I have a Warner Marine which works well but I am currently researching bigger better and badder, well not bigger, space under even a 300 dd is premium mine is centered in a room so no fish room to put equipment.
Running a cube I would ask the same question, Is OK good enough to,help protect your livestock?