Fistly how are you fueling before?
Next up is how hard and how long are you going for?
For long and strenuous rides without a break (races etc) I try and stick with small and often swapping between bars (Cliff/Torq/Supermarket Museli ones) Cliff Shot Blocks and Gels when needed. If you fall behind you get too low it’s really hard to get back on track.
Add in banannas etc for variety.
Drink wise depends on heat and whatelse is going on but the Torq energy drink does me well – about 50% strength for a general ride, full strength for racing.
Others will come along suggesting real food etc. lake sandwiches but for me getting the right stuff conviently and in easy to eat/pack/find/prepare etc.