If ext2 & ext3 are the only choices I'd pick ext2 for the internal flash device (microSD cards that will be very cheap to replace by the time they are out of warranty are a different matter).

Running out of power should be an exceptional event, while the journalling is active the entire time the filesystem is mounted. While it's on, every time you change a single bit on the fs the system will have to re-write at least two entire eraseblocks on the flash (one for the journal, one for the actual filesystem data/metadata, depending on the mount options used). Wear-levelling or not, that seems too excessive for my liking.

The main issue IMHO is handling an interactive e2fsck when things go pear shaped (but ext3 doesn't eliminate the need for that completely either).