There isn't a really big difference between them. Version 2 is somewhat more detailed and uses different symbols than Version 1 to represent the measurements of Latency, History and Uptime. You may also download TXT versions of each. Most users need only consider which stats version their client will read. Here is a summary of the recommended version.
Further comments are below.
Pick a format that you like and stick with it. I tried it a while ago, and it had no reliability data when I made chains. Frog-Admin says that JBN1 only reads version 1 stats. In that operator's experience, JBN1 works better with HTML files than with plain text files. Private Idaho As for Private Idaho, there are lots of different variations of this older program.