Most karate besides kyokushin is a joke for real fighting (ie lyoto machida). I found it to be a good stepping stone to go into other martial arts from though. I have to disagree on judo being a joke though, i prefer greco roman grapping to judo as judo relies so heavily on the gi, but i train with two judo blackbelts regularly and i wouldn't dream of picking a fight with them. once you learn to adapt judo technique to overhooks/underhooks instead of gi it can be very devastating. I dont think japanese jiu jitsu is superior to BJJ at all though, BJJ has been proven time after time for years to be far better adapted to MMA, 10th planet jiu jitsu is specifically built around no-gi grappling for example. I would personally say Wing chun and other kung fu styles are a joke. martial arts like that really are more of an art than an effective fighting style, the only way any of them can work is if you're fighting somebody of the same or similar style, or like as you said, devote your whole like to it which is why nobody ever uses them as a part of mixed martial arts training, it's simply not worth it.(
With regards to strength and conditioning, i think it's important to train smart, everybody has a different style and it's important to train right for your style (eg a striker would train for explosive power as opposed to a grappler training for strength.)
I couldn't have put that better myself