Trading pitching for bats - what's fair?

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I'm in a 5x5 NL roto league, and I'm at or near the top of most pitching categories and at or near the bottom of most offensive categories. I'm looking to make a trade with another team in almost exactly the opposite situation. Specifically, I'm targeting David Wright, Chris Young, or Neil Walker, with an outside eye towards Alex Gonzalez or Orlando Hudson. Which of the big three do you think will give me the best bang-for-my-buck return in terms of producing in as many categories as possible? Of the pitchers I'm willing to trade (Chris Carpenter, Jhoulys Chacin, and maybe Kyle Lohse, as well as Brian Sanches and Travis Wood who are both on my bench), with consideration that I could throw in a "filler" player like Tony Gwynn, Jr., to the trade, what combinations would be fair?

Thanks!