Heh.. dangerous thread here... According to our rules:
(8) No BSD vs. Linux vs. Windows or similar threads.
and really that is what this will ultimately come down to. Some discussion is possible, but after that we may close the thread.
ext2 is clearly not ready for prime time. Without journalling, a filesystem can't really compete today. ReiserFS offered journalling first and some distros switched to it. Other stuff was large file and volume support. ext3 finally came out and possibly surpassed ReiserFS. Between ReiserFS and ext3 reasonable minds can disagree. Development is continuing on both. Both have supporters who make various claims. Making ReiserFS a default is a way for one Linux distro to distinguish itself all the others. Considering that they all run the Linux kernel with GNU utilities, thats not real easy to do. And you can't flip-flop back and forth without alienating everyone.
Perhaps neither will "win" and ReiserFS/ext3 will join HP-UX/SunOS and Suse/Redhat and all the other muliple choices we have. It seems a little wasteful, but the competition is actually very healthy.
Sun did some benchmarking... see: this paper (PDF file).