I would definitely do trade 1. Carpenter would add a big, solid, and consistent arm to your rotation. And you can absolutely afford to lose a 2B with the talent you have to back him up with Prado, Hudson, and Uribe.
I definitely would not do trade #2. I'm not a fan of Pena at all. His average will drain your team and his only upside, power, seems to be streaky. Miggy will be a top 5 draft pick next year whereas Lincecum (top pitcher drafted this year) will fall to around 3-5. Plus you have some good young arms like Strasburg, Hughes, Bumgarner and Hunter going forward.
Trade 3 I wouldn't do either. Breaking it down, I would MUCH rather have Miggy than Halladay. I will always take one of the best bats over one of the best arms. So comparing the others, Adrian Gonzalez gets a slight nod over Dan Haren and Delmon Young is better than Bobby Abreu. So if those 4 players balance out (which they roughly do in my opinion), then it comes down to Miggy for Doc, which I already said I'd go with Doc.
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