I use the original energy gel, honey. I found a supply of honey in pouches like those used for ketchup at fast food places. They get me up the mountain.
Also, I eat Clif Bars, Cashews, peanut butter/cheese crackers, and dried apricots on longer rides. I carry Powerade Ion4 drink mix in small plastic bags, one bag per bottle of water. Endurolytes to keep the cramps away. Yes, I eat a lot and drink a lot on rides. Through various and sundry experiences, some good, some bad, I've found that this is what works for me. I was, for all intents and purposes, self sufficient on my last century earlier this month. All I needed was to reload with water at the stops.