I use both. Both are excellent filters. I use the AC 50, 70 and 110.
I also have 2 Penguin 350 and they are very inexpensive. I purchased them
for $26.99 each. I got the AC 110's for $32.99. So, the Penguin were actually cheaper.
They both put out lots of flow and keep the tanks nice and clear.
With the P350 I change or rinse the pads weekly and the AC's are rinsed weekly
and replaced monthly. So, for me it is a toss up.
BBOY
I also have 2 Penguin 350 and they are very inexpensive. I purchased them
for $26.99 each. I got the AC 110's for $32.99. So, the Penguin were actually cheaper.
They both put out lots of flow and keep the tanks nice and clear.
With the P350 I change or rinse the pads weekly and the AC's are rinsed weekly
and replaced monthly. So, for me it is a toss up.
BBOY