Its time to get a portable system. Should get a DS Lite of a Gameboy Micro?

I never had a gameboy advance and there seem to be a lot of good games for it but at the same time all my friends have a DS. I know the DS can play gameboy games but are there enough gameboy games out there for me to just get the cheaper micro and make it last till the next system comes out? Another thing I'm worried about is the portability of the DS Lite. Thanks.