I waited quite a while till ext4 was stable ... it's stable enough now, with many advantages, it's my choice now for all my partitions.
Without a doubt ext4
Ext4 supports all of ext2/ext3 functionallities and a *lot* more.
The one I like the most: *fast* file system checking (and formating)
You've got barriers as well as delayed allocation and many many other things.
Trust me: go for ext4
In the case of production stability ext4 might be a bit of a scare for the more conservative, not that I have noticed anything but on the other I've not seen any test on the stability on high I/O storage systems (for that I use ZFS) and also if you feel the need to have a great /home partiton filesystem I would look at xfs since that + LVM equals awsome...
Here are some fun reading: http://www-958.ibm.com/software/data/cognos/manyeyes/datasets/89ade5ae14209c140114bcee8c082d35/versions/1
Also a mention to prevent flamewars the when at the crossroad of selecting Filesystem I most often run with a simple use what you think is right. Like stated the difference between ext2 and ext4 is mainly in the journal and around 20 years of age :). New is not allways better though.