My vote goes to:
These are the 5.5mm bullets. I like them for a few reasons:
1: Very easy to solder. You cant overheat/warp them.
2: Much larger contact area than most other connectors, thus less resistance.
3: The cross-sectional area of the conductor is tha same as a 10AWG wire so they can handle loads of current as well.
4: They aren't too large. Though I've seen them in sizes up to 10mm.
Deans are OK, but if I were to use them I would use a whole connector on each wire. That would be about the same as using these 5.5mm bullets.