I think 250g is my favorite. They always seem to last a while, and if you buy some new stuff you can put it in the collection. It was so awesome when I had like 10 flavors to choose from.
What I've been doing lately is buying two or three 50g and mixing them together. 1.99 for a 50g of cheap shit, mix it all together, and I always can get pretty good blends. Orange-vanilla-mint is pretty damn good, so is kiwi-strawberry plus a little bit of mango.
I always find the best purchases though if you go the good quality like pharaohs and just smoke what they have. MMM.