When considering what tools to carry, I first think about what the most likely things to go wrong are, and then choose the tools I will need to fix those problems.
Change a battery
plug a hole in a tire
pull a wheel off and remove/replace tire
adjust a belt/chain
adjust/tighten footpegs, shifter pegs, mirrors, throttle and clutch cables
jump start a bike with a dead battery
put gas in an empty tank
repair frayed/broken wire
replace fuses
replace bulbs
change sparkplugs
I end up with a set of combination wrenches from 5/16 to 3/4, with extras
in a few sizes (sometimes you need two of the same size wrench) plus a 10 mm for the battery and a 15/16 for the rear axle, a set of 3/8 drive sockets from 1/4 to 3/4, along with a nifty little Snap-On short ratchet, a few 3/8 drive torx sockets in the sizes that fit fasteners for the above jobs, a set of ball-end allen wrenches. A screwdriver with interchangable tips. Pliers, wire cutters, small and large vice-grips. (I once rode 750 miles using vice-grips as a clutch lever)
A small assortment of fuses, a small assortment of wire conectors, a crimping tool, wire ties (including a few extra large ones) electrical tape and a circuit tester. A small roll of duct tape and some bailing wire.
I have a gas can that is form fitted to a Harley saddlebag, a lightweight pair of jumper cables, and 6' of fuel hose, that I can use to siphon gas or cut a section to replace a bad fuel hose.
Tubeless tire repair kit.
Probably sounds like a lot, but it all fits in my right saddlebag and goes with me everywhere. In the last 50 years of riding I have used every one of these tools at least once, more often on other's bikes than my own.
For anything I can't fix with the above stuff, a cell phone and a credit card.
Of course, you need to consider your own mechanical skills and knowledge too. No point carrying a bunch of tools you don't know how to use. And no point carrying cheap tools either, they usually break at the worst possible time.