Well technically you can get good 2D out of every graphics chip ... getting the analog line filters right is the important thing in making a graphics card give good 2D quality. There is no extra cost involved.
That said, I've never seen an ATi card with bad 2D, but I've seen too few SiS chip based cards to judge. Those I saw were OK, but given their cheap nature, I've never seen them combined with really good monitors ... people who need to save $20 on the graphics card usually don't have $500 monitors ...
regards, Peter