If you're talking about skimmers integrated into inflow/outflow, I prefer skimmers that go on the inflow so the biofilm is taken to the filter for processing instead of being spit back into the water column, which is the case if your skimmer is on the outflow. Quality-wise and looks-wise, they're all the same; I've ordered from a few companies so far—FZone, Jardli, and another Chinese one—and I can confidently say the only difference is the markup. They're possibly made by the same manufacturer in China and sold to the various western distributors. Some people struggle with these inflow skimmers due to either a lack of flow or too much flow, which sucks air in. So if you want to use an inflow skimmer, you need a strong enough filter with appropriate flow adjustment valves.
I have had instances of fish being sucked in, but once they get used to it, they know how to deal with it. The shrimplets do occasionally get sucked in, but I'm sure we all find the occasional shrimp inside our canister filters.
