i think its personal preference.
from my experience
For a small tank - a HOB
is the best
for a large tank - a canister is the best
for a very large tank - a wet/dry filter is the best
for a 37 gallon - i think a canister would be the best.
but again, a HOB
is probably cheaper and you can probably buy 2 HOB
for the price of 1 canister.
i'm a big fan of Aquaclear HOB
- they are probably the best HOB
in the market
there was a thread concerning HOB
vs Canister a few weeks ago
You should check it out, some good points are raised.
a strong point that was raised regarded the GPH
could provide a much greater GPH
turnover rate than 1 canister.
is this what you want ????
and as I said above - it would be much cheaper too
Also, you wouldn't even need an airstone, since HOB
's provide the greatest oxygenation. This means one less electrical equipment (no airpumps/no airstones) and more room in your tank
Also, the aquaclear is SUPER SUPER quiet, so you will never have to worry about airpumps or noisy canisters (some can be noisy)
the downside of HOB
is that you need space at the back of the tank and it is not as easily hidden compared to a canister (although a canister can be unsightly especially if its not stored in a cupboard).
Hope that helps.