All of them are great. It really depends on what you plan on using your cart for.Here are the MicroSD cards I'm looking at. Which would you say is the best?
http://www.newegg.com/Product/Product.aspx...N82E16820134562
http://www.newegg.com/Product/Product.aspx...N82E16820134215
http://www.newegg.com/Product/Product.aspx...N82E16820134478
Each gig will hold about 20 games give or take. If you plan on having other stuff like media and whatnot then I recommend a 2gig as that is what I have always used and never had any issues of not enough space. When I used a 1gig, I ran out of space fast and I went out to buy a 2gig. I would say the 2gigs are very solid and at a good price to match. However, at that price the 4gig seems to be a great option too. I highly recommend the SDHC if you know you are going to get a card that supports it since not all of them do. Basically, if you are going to make your flash cart + DS an all purpose media and games machine then the 4gig is for you. TONS of media like movies and music can fit and also MANY games can be on it too. I recommend the 4gig if you have a card that supports SDHC.