I carry as little as possible!
So generally, no bag at all. That goes for both road and MTB.
In my pockets:
mobile phone plus cards, cash etc in cycling wallet
energy gels
small pouch with spare tube (my bikes tyres are tubeless)
tyre levers
C02 thing plus cartridge
mini pump
multi-tool
However! On my gravel adventure bike it's a whole different story. I've recently received my custom colour Wizard Works bar bag and top tube bag. I have a set of all the above in the gravel bike already - the 'secret' down tube compartment behind the water bottle (Specialized Diverge).
So the bags are for extras. Still deciding what those 'extras' might be!
