Go with the Rena. I've had an XP-4 and an XP-3 running for two years straight with not an issue. I had a Fluval 405 for about 6 months but sold it and replaced it and here's why. (1) The mechanical filtration sponges are vertical on the Fluval and I noticed sunstantial uneven collection among the sponges which means there is uneven flow through this collection area. (2) The media baskets on the Rena are bigger....why, because they don't run their sponges vertically they are on the bottom and lay flat. They even give you two sizes of sponges to run. (3) The hose set up and intake and exhaust IMO on the fluval is poorly designed and cheap. Although I really dont understamd why Rena makes their intake tubes blue...maybe that was the designer's favorite color. (4) Rena is quieter than Fluval IMO.
Check out the Eheim Classics which I also have. You will spend a little more but they are super quiet and worth it.