1. Baseball is a far superior game overall.
2. TONS more strategy, more fun to play baseball as a fantasy sport because of that. In fantasy football you show up, try to get 3 of the top 10-15 RB's and you can typically march to your championship. 6th Graders can figure it out. FB is like a season-long game of matching wits with your league rivals.
3. The draft/auction is way more fun with baseball, because there's such a deep player pool to choose from.
4. You don't have to draft kickers in fantasy baseball.
5. 162 vs. 16, games played everyday vs. once a week, which also equates to a longer season of smack-talking.