I got curious about this after seeing a recent APOD image of NGC 5128 (Centaurus A) which described it as the fifth brightest galaxy in the sky (relative to Earth, obviously)
So I guess that would be after the LMC, SMC, M31, and M33. The first two I've never seen due to my northerly location. But although overall M33 might be brighter, it is far less easy to view telescopically than M81 or M51, for instance. I have only seen it twice, and I can nail M81/M82 from my suburban backyard within seconds. From up in cottage country I was actually able to view them in a 60mm refractor.
So is there a list of galaxies suitable for small to medium scopes sorted by surface brightness rather than overall brightness?