Try them both for a few years. There is no way either one would be useful to you in less time than a few years (unless you are a fanatic and trained daily, hard). Either one is good, each takes different approaches. Jujutsu utilizes more pain/compliance, Aikido utilizes more structural weakness and leading. Both work kuzushi, just different ways of getting there.
If winning fights is the real main thing you want to accomplish- run, lift weights and discard your conscience, you'll be just fine. Just remember, fights hurt, and you aint getting any younger.