I use hive top feeders - easy to refill without opening up the hive, fewer spills, hold fairly large amounts. The wooden ones tend to mildew.
I like the inverted bucket feeders even better (hold even more, easier to clean) but I use horizontal hives with migratory tops - no inner cover to rest them on!
The biggest commercial keeper in my area swears by division board feeders, and I've seen him leave them filled next to a cluster over winter. They tend to drown a lot of bees initially, but eventually the corpses form a raft. Looks like they work fine but I have too many hives scattered across the county to want to make that many refilling trips.