Is he the unquestioned best UGA QB ever?
It depends on how you're measuring success. If you're looking at college stats, then definitely not. Stafford threw for 7700 yards with a 57% completion percentage. Aaron Murray obliterated Stafford's college numbers and is the SEC's all-time leading passer. Stetson Bennett won two national championships with Georgia, but his stats aren't near as good as Murray's.
Stafford is arguably the best NFL quarterback from Georgia. I'd say he's passed Fran Tarkenton for that honor. Stafford has better stats and won a Super Bowl.
I'd go as follows:
Best NFL QB: Stafford
Best statistical QB: Murray
Best winner: Bennett