It depends with me, depends on distance and terrain.
Long distance (> 50k ) and rough Bridleways stuff I tend to carry a camelback with spare tube, puncture kit, spoke key, lezyne multi tool, couple of gels and bars, wallet, phone, cards..
Long distance (> 50k ) gravel route (something like SDW/Ridgeway) then bottle, puncture kit, multi tool, wallet (contains money/phone/cards) couple of gels and a bar, all in rear Jersey pockets.
Short distance or routes I know well then just simple puncture repair stuff, phone, money a gel maybe a bar, in Jersey pockets.
In the main I take stuff in 2 above, seems to be light enough and concise enough for the riding I do.
I did the Lakeland Monster the other week, I took a camelback full of crap expecting the worst that the terrain could throw at me, however I could (and should) have done that event with stuff in No2 above, that would have been more than enough.
I’m about to do the Wessex Ridgeway, means a stop over and the terrain looks fairly easy but because it’s a long distance and near all off-road I’m taking the camelback set in No1 above. Looks about the right kit I’ll need for me rideout.
I don’t get on with saddle packs very well, I much prefer the lightness of the bike, but with the expanding distance I’m intending doing/starting to do it looks like I’ll need a seat pack and possibly a frame bag/bar bag and I’ve started looking into this. Quite what I’ll carry in them I’m not too sure, but certainly tools I have are adequate, maybe just a spare Jersey or something else etc.
Most distance stuff I do takes me near/past/through villages etc. so all I need regarding food/drink etc. is catered for that way so I’ve no need to carry coffee makers/sausages/bread makers/food mixers 😆