Ahhh nutrition. You would think with as much as we eat we'd have a better understanding of this subject, but alas...
It confounds the best of us and leaves the rest of us either bonking or well, making pit stops.
The first, most common nutrition question in triathlon is, "What's the best nutrition?"
The most helpful piece of advice I can give here is - try them all and see what works for you! Seriously, try ALL of them.
Buy sample packs and use one kind of nutrition for a couple weeks, then change it up. See how your body responds to each and use the one your body (and mouth) like the most.
Next, "How much do I need?"
The body can deal with up to about 300 calories per hour. So use that number as a guide. Some people may do well with 250, others may do well at 400. Keep experimenting and see what number works best for you.
Lastly, remember it's ok to mix and match!
What works well on the bike may not work well at all during all the jostling of a run. What your stomach can handle during a sprint may be different than during a slightly lower intensity olympic. And your body will almost definitely respond differently at mile 20 of your Ironman run.
What have you found working for you?