I have been using UDF format for all my data DVDs since Nero recommended it one time when I tried to put a very large file on a disc. They seem to work fine for the most part.
I just ran through the SmartStart wizard to quickly create another data DVD with a bunch of small files and Nero automatically chose ISO+Joliet.
Which is the most compatible format to use for data DVDs that I will want to be able to read back in years to come? I mostly use Windows systems but once in a while I have to trade discs with Linux systems but that is not a priority.