I use the small kibble from Pedigree Better By Nature as general basic treats - in pockets for walking, or in a small box by the back door. I mix this with other 'dry' treats so it's easier to bung a handful in my pocket.
High value treats for mine are soft meats such as chicken, sausage or ham, and I use cheese too. Because they go mushy I tend to put these in a plastic takeaway container and I can get amazing recall just by taking the lid off!! High value simply means something your dogs will do anything for

Something else that works really well for mine is salami sausage stuff from pets at home, it's a bit greasy and garlicky and mine love it. It's half way between wet and dry and it's a good one to mix with other treats as it spreads it's flavour and smell around. I don't like feeding
too much of this one though as I'm sure there's nothing much 'good' in it!!
When I have all this stuff in combination the dogs never know what's coming out next so they tend to keep me within sight - just in case I put my hand in my pocket...
Something that can help with dodgy recall is associating the treat with a whistle. Start in the garden first and every time you blow, throw your dog a treat. Gradually bring the treats closer to you, then reward with collar held, then lead attached. Your not training recall as such but letting your dog know that the whistle equals food. Sometimes, at random, give a handful of food. This will help a food motivated dog to pay attention to you. Finally before you go walking let your dogs see you loading your pockets with food
Kindness is the language which the deaf can hear and the blind can see ~Mark Twain