I'm updating my HTPC and it uses 3 80mm fans, 2 on the back pushing out and one pushing down, and there isn't room to use a larger fan. The fans that are in there are pano fans that came with the case (OrigenAE X11) and have been running for about 4-5 years. I'm doing some upgrades to the case and want to replace them as one of them has gotten louder.

The recommended list of 80mm fans seems old, so I was wondering what the current recommended fan is? I'm thinking of going with a Scythe S-Flex or Kama Flow, but don't really know what the difference between the two are.

Thanks,
Mike

Nexus and Noctuas have a good reputation.
I tried an 80mm Nexus and it was decently quiet for a small fan.

I don't know the 80mm Kama (I own only 120mm Kamas), but I have several Scythe SFF80A and Noctua R8: the firsts are costly, very effective, enough quiet even at full speed, inaudible up-to 7-800rpm even at 10cm from my ears, while the latter here is overpriced, wonderfully sleeved, very flexible, and inaudible up to 900-1000rpm (but as I use them for PSU fan swaps, so I can't tell if the speed have to be dialed down when used as case fans). I may also recommend the Sanyo Denki Petit SanAce, but it's very costly and less effective (it's a slim one).

For vertical mountings there are several cheaper sleeve bearing alternatives (Xilence, AC, et c.), the most notable being more probably that not the venerable Nexus Real Silent Case Fan (which I also own).