I am going to say the best multi tool is the one on you. I carried a Leatherman PSTII for a couple of decades, before that, I carried a Swiss Army knife. Though I carried this Tinker for years, having the Phillips head screwdriver in the middle of the handle made loosening Phillips head screws tedious and frustrating. The Super Tinker was a bit larger but handier.
The handles broke and I glued them with Devcon epoxy. Eventually I sent the knife back to Victorinox for refurbishment. It is in my travel bag. Still goes with me on travel to Regionals and National Matches, but stays in the room.
I sent the PSTII back this year to leatherman, to tighten up the handles and replace the worn standard screw drivers and file. Leatherman did this for free, even though I bought the PSTII in 1996. The PST fit into the same volume envelope as the SAK but had pliers. I cannot count the number of screws I loosened, or things pulled, because I had the thing on me.
When I go to the range, I carry my original Leatherman wave. It has selection of screw drivers that I have used many times on tiny gun screws. I have used the needle nosed pliers many times to clear jams in AR15's. Cartridges will jam feeding into the chamber and the loading port is too small to reach the cartridge without needle nosed pliers. I prefer the original Wave instead of the later versions that require bit attachments. It may make more profit for the company but the screw driver bit attachments fall off in use and they are cheap.
When I am working on my vehicles I am using either a Gerber Diesel or the Leatherman Super Tool 300.
The leatherman Super 300 has longer screwdriver bits than the Gerber, that is actually an advantage when trying to unscrew recessed screws. Big, heavy duty mulitools are bulky. I wear them only when working on mechanical equipment. If size does not bother you, go big.