I have tried both and I personaqlly found that the dextrose / glucose tablets fine with no problems.
I would keep them loose in a pocket thats not going to get wet ar damp, you can just pick them out and pop them in easy peasey . They are a bit chalky but in a wierd sort of way they also create a burst of saliva, not quiet opal fruits (or whatever they are call these days) but a little refreshing. No need to carry bottles around with you which I find a pain.
When I ran my first half marathon I carried two gel's with me in my hands, I am a bit of a tight arse and wont spend on gel belts etc however at about the five mile stage my hands became sweaty and one gel slipped away and i didn't stop to pick it because it was still very busy with runners !!!
If I was you try both on different long runs and see which one you feel works for you then stick with it on race day. good luck