It's a long thread... but I highly suggest reading through the "How Important Is Bio Media" thread in this folder... it will share most of my filtration perceptions with a couple of extreme examples of long term set ups I've had success with...
In short... it's silly to say "this for Bio and that for Mechanical"...
Bacteria grows everywhere...
Any filter that pushes water through media with minimal bypass can be a good filter... how easy it is to clean, how practical it can be set up and how much it costs are the 3 biggest considerations to be had...
In my experience, nothing beats an AC 110...
Very reasonably priced, moves a ton of water, when set up correctly has very little bypass, very quick & simple to clean......
In many years of experience... I've never had a mature tank with proper water movement suffer from ammonia or nitrite spikes... despite having never bought into the bio media hype...
In my experience, there is plenty of "surface area" in the typical system for more than enough bacteria to colonize on to convert the ammonia to nitrite and the nitrite to nitrate...
A wet dry does offer ideal conditions for bacteria to grow and therefore double/reproduce... but the bacteria has a 4~6 hour doubling time... therefore "speeding it up" means you can double the entire colony in 4 hours instead of 6... who cares...
There are many many many misconceptions about bacteria in our aquariums commonly propounded in this and other forums... The "How Important Is Bio Media" thread in this folder challenges a lot of them and someone else just made a thread in the General Aquatics folder regarding bacteria that I expect to hold a lot of interesting information as (if) it developes.