Supercard (miniSD)
+ Excellent DS compatibility
+ Can get up to 2GB in size thanks to miniSD
+ Cheap
- Interface isn't as polished as others
- Very bad battery life (3 hours worse than M3 in some cases)
- GBA compatibility not the best
- Sticks out a fair bit
- Need to be careful with purchasing the miniSD since some have slowdown (Castlevania intro movie for example will be jerky)
- microSD Supercard Lite will be released soon
EZ4L (microSD)
+ Almost flush with the Lite (still sticks out a few mm)
+ Excellent GBA support
+ microSD up to 1GB
- Interface isn't as polished as others
- DS support not the best but getting better
- The tiny bit it does stick out is still noticeable
- Cheap build quality, users have had to file down bits of plastic to even get the card out
- Slowdown in games (Castlevania intro jerky, longer load times), unknown whether this is the EZ4L or microSD's fault
- 1GB microSD is expensive