I carry different tool kits depending on what kind of bike I am riding. MOST of my bikes are British, however I have some Italian (Ducati & Guzzi) and several HD sportsters and Buells. I have some asian bikes as well. (honda CB 4 cyls, Several Kawaskis and a Suzuki TS250 Enduro).
On some of the bikes I swapped out fasterners to ease maint, For example some of the HDs and Buells used some odd Torx fasteners and can be troublesome so switched them to stainless hex socket heads. On British, there is a difference between restored and all stock and "optimized" which means I have upgraded them to sensible upgrades, (IE:Stainless fasteners, EI ignitions, Upgraded charging and lighting systems, and often different carbs than stock--Mikuni often)
So it can really vary depending on the bike, But I buy tools to KEEP on the bike, and simplify what I carry for example ONE screwdriver with multiple bits/tips. a multi tool setup for the socket heads, some electrical supplies and ALWAYS critical cables wrapped in plastic and lubed. Clutch cable, throttle cables, and repair kits for the cables. I can work with a failing front or rear brake but if i cant throttle or shift, then i am stuck.
I try to pack into a reasonable sized tool bag strapped to the bike, but if a longer trip, I carry a backpack anyway so will throw more stuff in there. For example on my Buells and later model Sportsters they run a rear belt, which is far more durable than a chain, but I am unlikely to find one on a long trip so will carry a spare, But I dont around town.