What art is better? There is no such thing. If you realy sit down and think about it there is no such thing as a unique art. There are only so many ways you can punch, elbow, knee and kick someone. Saying one art has something different than another is pointless. The difference comes in how that system is taught and how they train. There are always going to be the differences in stance and punching style (full fist rotation vs. qtr fist rotation). Are those realy differences or just preferences?
There are a few basics you have to have in order to be a efficient fighter.
1. know how to hit and kick properly.
2. Know the proper targets and what tool to use on them.
3. Have a good understanding of timing, rythem and distance.
4. Know how to properly condition your body for a fight.
5. Understand the importance of proper foot placement.
6. Have a good understanding of body mechanics.

People need to understand training for 3-4 hours a week isn't going to get you very far no matter what you study. The key is repitition. You have to reprogram your initial reaction and make what you are learning second nature. Understand that fights go to the ground or can be toe to toe, could involve more than two people. Having a multitude of fancy and complicated techniques isn't always good. Most of the time your not going to be able to use them no matter how well you know them. The reason for this is when a person is scared or in a stressfull situation the heart rate goes up. When your heart rate increases you loose motor skills. Between 150bpm and 170bpm you are pretty much working off of your gross motor skills. Your gross motor skills are the basic fundamental movements, complex punching and kicking will no longer work. One of two things needs to happen in order to be effective in this 150-170 range. Either you need to train your more basic techniques harder and focus on them, or train using some kind of reality sparing to try to stay more calm in a tense situation. Then there is always the fact that no matter how much you train and no matter how good you are in the dojo, will you fight? I've seen 4th and 5th degrees get handled pretty well on the street because when fight or flight kicked in there body chose flight and they got clocked. This is why the basics should be pushed so much.

Why train in just one, why not both karate and jujutsu. Or at least find a school that will teach you some of both.

hello,

as u can see im from brazil
here Jiujitsu is very popular. we've got the famou brazilian jiu jitsu. belive me, heaps people here do Jiu jitsu.

if u want to know if jiujitsu is effective in street fight i'd say NO.
ive seen some fights against JJ, and most of then they loose. why?
because u dont take a street fight to the floor like that. u cant roll on the floor and wait to do your arm lock.
in street fights, most of time u arent alone. people wouldnt just watch u get bashed on the floor.
another thing, is too hard to take u to the floor if u r good praticer of tkd, mt or kung fu. they came to take u down with their head down, easy to kick their heads.
if u still like JJ, keep doing it BUT if u r looking for street fights, start to do a stand up fight, id recomend muay thai, because muay thai and jj together is a good combination.