Archon : Incandescent Sage
Unit : King Erminaz Twincleaver
I think the above has the best chance of winning, as mentioned by many others before me, with same reasons stated by others.
I would like to explore another possibility, low one though of beating Jolius, that is:
Archon : thalgrimore
Unit : Necrulencian Thief max lvl
there might be a small chance to win over when jolius continuously miss hits Necrulencian Thief, and thief continuously poisons jolius, then win over.

I still think King has better chance of beating jolius, but just want to provide another possibility.