SD/SDHC then for best compatability I reckon. I usually get Transcend ones, they’re inexpensive and good quality. Also, I get ’em from trusted vendors- Which mag tried to do a test of memory cards bought online from no-names a while back to see what proportion were genuine, absolutely none of them were…
Don’t worry too much about class… You can generally get class 10 without too much price premium but compact cameras don’t have a great deal of need for it, I use a class 2 in my wee ixus and the only time it’s ever an issue is recording hd video as it buffers out after about a minute- card can’t quite keep up with the camera. In theory faster cards mean faster recovery time for photos- ie it can take the next shot faster. But in practice I can’t tell any difference between my 2s and 10s, I don’t think the file size is big enough to be an issue except on video.