I agree with the above. Bruce has a lot of potential but I don't think he is a top 40 keeper yet. Plus he is more likely to be around come draft time than Upton. Although I am not sure that you should pick him that early.
The 3rd choice is tough, and I think it you have 3 legitimate options: BJ Upton, Crawford or Haren.......with Upton being the best (but not necissarily the safest) choice.
Even though he is risky, I think Upton is your best option. His upside is just too high If the risk scares you too much though, I think Crawford would be a solid, and safer, option. Crawford may not have quite as much power as we once hoped, but he is still a solid player...and he's younger than you think (only 28)....so he's just entering his prime. I actually think Crawford is under-valued this season, but his upside isn't nearly to the level of Upton's.
The wild-card is Haren. Normally, I wouldn't recommend keepeing a SP in a league with only 3 keepers. But Haren is (just barely) good enough to consider holding onto as your 3rd keeper. Since Upton and Crawford are both border-line options as well, you wouldn't be crazy to keep Haren....especially if your league over-values pitchers and this will be your only chance to get an elite pitcher.
Bruce is tempting...and I'm a big fan...but I just cant justify recommending that you hold onto him with only 3 keepers. There's just no way that he is a top-50 player, even in a keeper league. He MIGHT be by next season, but he's not there yet.
As far as the level of players that will be available in the draft, you are going to have plenty of great talent available. You are going to have some of the 3rd-round talent still available (since a few managers will make decisions based on position scarcity and/or choose to overpay for prospects like Bruce), and almost all of the 4th+ round telent will still be there. Depending on exactly what draft pick you have, I suspect that you are going to like your 1st round pick better than your 3rd keeper.
Upton is your 3rd keeper. Im assuming there's 12 teams (so 36 keepers) which means there is going to be plenty of good players available in the first 2 rounds. Just from !yahoo ranks alone,batters 37-50 are: Matt Kemp, Brian Roberts, Aramis Ramírez, Kevin Youkilis, Russell Martin, Curtis Granderson, Álex Ríos, Brian McCann, Shane Victorino, Adrián González, Jacoby Ellsbury, Joe Mauer, Alexei Ramírez, Geovany Soto, Nate McLouth, Corey Hart, Rafael Furcal. Pitchers 37-50 include: Webb, Hamels, Papelbon, Peavy, Halladay, Haren etc etc
Let me put it to you this way; If you dont keep Upton, someone will draft him with a top 3 pick. Bruce, on the other hand, has a great chance of making it to your 1st round pick, if not your 2nd.