It depends on what you need on your team. If you had a team with strong popst players, then you would not need a player like Bosh. And the other way around. For exaple the 76ers definitely need a player like Bosh instead of a player like Carmelo Anthony. Bosh is probably better all around as well, Melo is more of a pure scorer.
Chris Bosh because he's bigger duh. Big are usually hard to find than small. Also I don't see Chris Bosh evolving his game like KG. One thing KG is better than Bosh is his unstoppable faraway shot and his presense on the defensive end. Bosh right now has a long way to go but I don't see him becoming a player like KG, especially on the defensive end. His face looks too babyish and dorky compare to KG LOL
I rather have Bosh because I would want a good big man over a good wing man. Now if the choice was either Bosh or LeBron, then obviously LeBron. I don't know I mean sure Carmelo is avg. amazing ppg but Bosh isn't a slouch either and gets over 10rpg. His blks are increasing as well and is learning to be a better post defender. Melo though can score doing anything. It's a tough decision but I choose Bosh.