I have a few rules with onboard tools.
1. It must not take up valuable storage space.
2. It has to take into account any accessories, which means a combination of metric and SAE tools.
3. I'm not going to spend much money. $0 is preferred.
4. I'm not going to carry Snap-On tools on the bike, but the tools must at least be reasonably usable.
5. I am not going to do major repairs on a trip. My goal is to be able to fix minor problems, or McGyver something together when needed. I have no intention to change a tire on the side of the road, or replace a bad alternator in a hotel parking lot.
6. The tools must be compact, to reduce storage space.
Below is a pic of my tool bag. It is an old shaving bag that holds everything except the meter, and it fits in the cubby hole in the trunk, on top of the CB. This is an old pic. It has changed slightly. I now carry a digital tire pressure gauge, and I added electrical tape and a couple of other generic supplies. The whole thing was built from spare tools that were in storage. I even kept a few wrenches from the original Honda kit that I felt were usable.
I hate L keys for large Allen head bolts, so I carry some Allen sockets. I still carry Allen keys for the smaller screws.
I was fortunate to have some Xcylite Series 99 field service tools. The master handles and separate driver shafts makes them compact and highly usable, without the risk of losing tiny hex bits.
The tool bag is on the bike at all times, but the meter is only on board for long trips. I do not carry full sets of wrenches and sockets. Everything is based on the hardware the bike actually has.
Not shown in the pic is my Slime air compressor and tire plug kit. The compressor has a Powerlet plug that plugs into a port I installed in the battery side cover.