For snacks that have no cooking required.. pickles, pepperoncini, cold cuts, sliced hard cheese, string cheese, nuts/seeds, peanut butter/cream cheese for celery/cucumber, tuna, and lettuce (both for salad and for making wraps out of the meats/cheeses). If you dont mind a little cooking i do frozen vegetable steamer bags of cauliflower, broccoli, or green beans which i frequently pick up for about $1/bag. Not as good as fresh vegetables but frozen steamer bags i find to be leagues above canned.
Stuff like beef jerky ($$$) or whatever is good in a pinch but they tend to have too much sugar added in to them and always make me regret eating them. Pork rinds are okay unless the seasoning is loaded with sugar.