I'm using JBINUP to post with based upon recommendations from other users. I can say for me it has been the most reliable and has never failed me whereas the other 2 I used before were quite flaky. I basically use all of the default settings and just plug in my username,password, and server information.
When I create rar's I've always set the file size to 100 megabytes per rar and selected no compression.
I use multipar because it works with win7 64bit and has a gui.