when I was starting out I bought a weeks worth of what I knew I liked, and then a few soups/shakes of other flavours on top to try, as well as the porridges. That way I knew I could safely try one and chuck it out if I hated it without missing out, and knew I had a few spares in case I fancied a change.
I'm fortunate though as I do like lots of them!
shakes I like.... choc, strawberry, banana, fruits of forest and vanilla. I make them all with extra water tho, about 350mls
soups I like..... vegetable (my fav with a splash of tabasco) chicken and mushroom, leek and potato, spicy tomato. I'll occassionally have an oriental chilli, but not often. I sometimes make a 'big' soup by adding a spoonful of the savoury drink stuff in with the soup mix, and double water.
Bars I like.... orange, choc, toffee and choc mint.