X fluval user. Too many problems with my 304 and 404. The 204 was fine, but the GF wanted it hold since my other fluvals broke too often and leaked. Switched to rena and never looked back. no leaking and no priming!
Would love to try marineland, but lacking the cash for that one.
From what I have heard and read, FX5 is great, so I think that should not be grouped with the rest of the fluvals. I think that is why it is winning since lots of people on here have FX5 which is much better than normal fluvals (at least from what I read).