Depends how hard you are riding and how your digestive system copes with different foods.
If you are bimbling round your ride in 8 hrs pretty much anything will work, cereal and/or cake bars from the supermarket will do the job nicely.
If you are pushing on a bit more, or if you struggle digesting fat/protein on the move you’ll want to stick to proper energy products.
Personally i like zipvit zv8 uncoated bars and SiS Go gels when going hard. When going easier, Powerbar wafers, kellogs breakfast bakes or whatever cake looks appealing at the cafe stop.
Edit: and whilst i know some people swear by them, jelly babies are not a smart choice when you do the maths on how many you need to eat to fuel a century on them alone