Bodog is better in every single way, traffic, software, and credibility.
Agree Bodog is better in the ways you list: traffic, software, and slightly on credibility. BetOnline is very credible as well though. While they are new to Poker over the last 6months, they have a well respected reputation as a Sportsbook as does Bodog so in this area it is closer then most people would think. I still give the edge to Bodog though because BetOnline chose to associate itself with the Action Poker Network which has had some past problems with affiliates and players. I should note though, that BetOnline is in control of their own cashier and is not reliant on the Action Poker Network. For those who still question whether BetOnline is on the Action Poker Network, I've been in direct contact with Pokerscout and they now list BetOnline as a skin on the Action Poker Network.
The only area I would give BetOnline a slight advantage is in player ability. In my opinion, BetOnline clearly has weaker players and more of the weaker players while having less 'regs' at most stakes.
Other than that one area, I give the CLEAR edge to Bodog in terms of software, support, traffic, and a slight edge in reputation.