Which Mora, SAK and Leatherman? I'm not a fan of Mora's, but some are so I have a bias. I have a Necker and while it's a good knife, it's a bit small in the handle for good gripping. If the SAK is a Rucksack, Outrider, Trekker or one of the other models with a larger locking blade and saw you may have a keeper, otherwise drop it. Leathermen are heavy and while you may find a couple tools useful, you still carry the whole thing.

I'd keep the mini-RSK in my pocket as it's a good knife to EDC and keep the SRK in the pack. Then I'd look at the SAK and Leatherman and take the one which adds the most to the two good blades you carry.

Really, I have a similar collection in my pack. SAK Trekker, Leatherman Original, Dozier General Utility, Fehrman Peace Maker and RSK Mk 1 -- all keepers <img src="/images/graemlins/wink.gif" alt="" />