I like the Cascade, priced right and easy to maintain. As for the bypass comment, there is a super easy way to fix that, tip I found on MFK's. Get a sheet of filter pad and cut 24"x1' strips off the end. Wrap each basket (or just the bottom one, or...) before installing it into the canister, done. No bypass and all incoming water gets filtered, I did this the last time I changed the filter pads and last i checked the bottom pad was green top to bottom.
As for size on a 55 gallon, don't go less than a Cascade 1200, unless you have multiple filters running. I aim my spray bar at the top of the water and I have plenty of aeration. I also have a Hydor IV sponge filter for additional bio (@5PSI air pump pressure) and a Magnum 250 for additional mechanical and water movement. All of these are on a 90 gallon with a medium to heavy bioload with great water parameters and clear water. (0 ammonia, 0Nitrites, 20-40 Nitrates when checked last and I had been feeding heavy).
