Indeed, my own favourite is oat groats, and I always take a sack in the car when going on any session in Europe, regardless of venue. On lakes with soft, muddy bottoms particles with a flattish side, such as black-eyed beans, maize, pinto beans, lupins or tiger nuts will settle softly on the bottom and can be easily taken by our friend, Mr. Carp. A hard bottom is ideal for the denser particles, such as soya beans, maples or chickpeas, where sinking out of sight isn't a problem. With weedy, silty type bottoms, I prefer to use very small particles, such as oat groats, hemp, pearl barley and the now famous Hinders 'Partiblend', which all sit on the weed nicely and don't sink out of sight. Of course, your rig must take that into account, so we'll look at that shortly.
Cost is an important factor also.
Particles such as tiger nuts are obviously far more expensive than a sack of maize, so you'll have to look at this when making your choice. I fish a lot of very big waters, which require fishing at huge range, so there's no way that spodding or 'bait rockets' as they now tend to be called, would be feasible. Mind you, it's useful to have this bit of kit in your tackle box. When dropping particles from a boat, if I'm using a reasonable quantity, I use an old piece of drainpipe and simply prefill it and tip it vertically when in position so that the baits drop accurately into the precise location. As I've stated in previous articles, I like to keep rigs as simple as possible when fishing in France.