probably judo. Unless you're a great thrower just by default, maybe with a background in wrestling or something, most BJJ guys don't have good throws. In fact most gyms start 99% on the mat. Knowing how to fight is great once you take down the opponent but doesn't matter if you can't, and pulling guard isn't a great option for a fight depending on if there's room or if the other person is gonna drop their weight on you and crush you into the concrete. So in terms of pure bjj vs judo it depends on a lot of factors, but in my opinion, bjj proves it usually wins in an enviornment without concrete, such as maybe on grass or on a carpet which to me seems like an unlikely fight environment.
Since judo has the throws and all that, I know bjj teaches throws but not nearly as often and they don't really spar with them. I think the bjj guy will be able to more consistently take the fight to the ground in order to employ their grappling or ground and pound. That and if it's a scenario where extreme force is warranted, such as the opponent just punched your kid or something, a judo throw executed with force had the potential to break bones and cause concussion. Pulling guard or doing a sloppy gracie style single leg doesn't have the same effect.
If you can training, mma is probably better than either. The gym will probably have a wrestling or judo class to cover throws and it'll have a grappling class that's more complete than just pure jiujitsu. plus you'll learn boxing and kickboxing so you'll be able to enter the clinch against someone punching against you, or just be able to dodge punches to run away. I think the style vs style stuff is stupid. Jiujitsu is a lot better for somethings and judo is a lot better for some things but if you take both of your strengths you'll be able to kick either the judo or the bjj guys ass.