I use EFS (Electrolyte Fuel System) bars by First Endurance. They have 250 calories and 40 g of carbs in each and have a great consistency. Easy to eat...and I drink water. Peanut butter/chocolate chip.
No stuff in the bottle other than water.
I have also carried Evervit GT Sport Tablets to eat. The advantage of those is that on a longer ride you don't have to carry extra drink mix in a bag or something when you refill your bottles. You can eat the tablets and drink water with them and it's the same. No mess.