That depends on what you want to spend.
Anything Eheim if you have the money. I've never had an issue with my ProII, and probably won't. You can't match the engineering, reliability, or build quality.
In the middle cost-wise, there's Fluval. A 304, 404 will work on a 55, or possibly an FX6 for high flow. These are solid filters that do the job.
At the low cost end, some people swear by sun sun filters. I really can't blame them for the price, but I've never used one, so I can't speak for their build quality or reliability.