Are you going to use a canister filter for a more silent sound? Or since your a fan of ambient noise, you'll go for the soothing sounds of water trickling down from an HOB? LOL
For filtration i was planning on an Eheim 2213. I have the 2215 and 2217 running on other tanks, and IME you cant go wrong with them. HOBs always end up going from trickling to rattly for me.