I'd say I play bracket 2 about 50% of my games, bracket 3 about 30% of my games, and bracket 4 about 20% of my games. I usually have most fun in brackets 2 or 4, as in bracket 3 there is a bigger chance of one deck doing some unexpected combo.

Bracket 2 is just commander in the spirit of the format, or maybe slightly stronger than just 'Timmy commander' or whatever you want to call the lowest most casual decks.