I'd be willing to bet you'll get a different answer from everyone who posts on this thread.
For me, Gu is the best tasting gel. I like espresso love, triberry, and just plain over the other flavors. I got sick of vanilla and chocolate is too thick - like frosting. Bleh. I keep a Gu flask, which will hold five packets, in my Bento Box right in front of me, and suck some down every 45 minutes or so on the fly. I'll eat an energy bar, Luna usually, while stopped perhaps, but not while riding. Same with Sport Beans and Bloks. Too difficult to unwrap. Plus I don't like having bits of food in my mouth while riding. Gu solves that.
I carry only water unless it's hot out or I'm riding over 50 miles. Then I'll add Cytomax or Gatorade powder half strength to one water bottle. I carry it with me in tiny ziplock bags made for beads. Michael's crafts sells them.
I get Gu in bulk at REI so I get the discount when I buy 12+ of an item.
I think the best thing to do is just experiment until you find foods that you like and that work for you.
Health is the thing that makes you feel like now is the best time of the year--Franklin Pierce Adams