I'm late on this but for anyone interested, my faves are
Fiber Select Wheat Thins (regular flavor)
All Bran crackers
Thin Triscuits (Quattro Formaggio, yum)
wasa
But, if you are looking for something good to put tuna on, my favorite thing is slices of cucumber. Crunchy and they go so well with tuna! Thin slices of daikon radish, placed in ice water, are also yummy, sweet and crispy with tuna.


