I mentioned my Swiss Champ. That's my favorite knife of all, and is a multitool, but not so much for heavy work. It's better suited to light and delicate work. Electronics, manipulating small cordage, woodworking...
When I'm geared up to do work, I carry a leatherman. I lost my original PST, but now carry a foldable version unfolded in a sheath. It has almost no tools, but it does have the fullsize pliers, and that's what I really want. All the other tools are bettered by my other knives I'm carrying. The problem with the leatherman(at least the original) was the steel was too hard. I broke almost every tool in my original PST. Generally hard steel is a good thing, but I abuse these portable tools to make magic happen. It's the tool I have with me, so that's what gets used/abused. Swiss army uses fairly soft steel. They can deform, but be knocked back in shape. The blades dull fast, but they also sharpen fast. The leatherman just snaps off. Dunno if their more modern tools use a different steel, but the original models were only really good for the pliers, but those pliers were compact, and could do a lot of work. Worth it just for that.