Apples and Oranges, IMO. The Swisstool is a heavier duty, more durable and stronger tool. The Wave (most popular of the Leatherman line, IIRC) is also very high quality but a smaller and lighter tool - much easier to carry. I've never had a Gerber, but feedback I've read is variable. OTOH, the SOG is getting some very good raves, I want to play with one.
There are multiple Leathermans and multiple Swisstools (and multiple SAKs, a different animal altogether)). You can probably get better answers if you say which models you're referring to (is it Crunch only?). If you're looking at a whole line, the Leatherman line is much bigger than the Victorinox (I think there are 4 models of Swisstool, but they're all close to the same size and quite similar).