Depends on what you want to do with it and how much memory you want to use on it ?! Want to use more than 8 Mb ? Then this rules out a lot of cards. Want to use 128 Mb ? Then you need to take a choice out of nto so many cards I think ..
And how much do you want to spend

The memory is not that important these days so with or without memory won´t make any difference if it´s 16 Mb or below ...