I have used Tunze and the hydor koralia. Tunze all the way. Been running over 6 years with only cleaning stopping them. Koralia I have had many break or begin to go backwards or stop working. I also have the gyre Maxspect, but for a 55g that is too much. I also have a jaebo 10 maybe (I can never remember all these letters and numbers) and it is holding up so far after 1 year and 3 months.
If you can budget it, I would go with Tunze, but know that Sicce is coming out with some nice competition. Anyone on those guys?