NFS vs AFS -- which is more robust?

[zeek]

I want to provide network access to a lot of small files (250 million+). New files are being created all the time.

I'm leaning to using NFS in read only mode. RW NFS seems to be unreliable (judging from the NFS mailing list). Can anyone with NFS experience comment?

Recently someone suggested that I look into using AFS -- can anyone with a deployment of AFS on Gentoo comment? AFS seems rather cool, but using it for a single locally attached disk from a single server isn't the ideal usage of AFS.

Overall I need a system that is reliable.

TIA!