I like both fights, and would be content with either. It would be cool if Bradley was on the Pacquiao vs Clottey undercard to set up a fight between the two of them if Pac wins.
Considering just a single matchup then I would prefer Bradley as the opponent. If Pac is considering staying in WW for future fights such as Mosley/Berto or Floyd then jumping up and down in weight might not be a good idea. Might as well stay on WW to get confortable with the weight against a tough enough fighter in Clottey and prepare to fight the best at WW soon after. It would be unfair to ask too much of Pac fighting the best everywhere while people complain about catchweight. Just as people wouldn't like it if Bradley has to come up to 147 and fight the best there. Making Pac fighting the top fighters at 147 then jumping down to 140 to fight the best is unreasonable, especially if he has to jump back up to 147 again to fight the best in the near future.