Everything everyone on here has said about Judo, is true.
That having been said, let's look at it like Mike said, from purely a training standpoint.
You're going to learn ukemi, falling, and get some great conditioning.
You will learn the eight directions of unbalancing and measter them in no long time, within six months.
You will learn to throw an uncooperative opponent who is trying to throw you and take you down.
You will learn how to block throws.
You will learn some Proper jointlocks(by proper I mean they flat wil work, no ifs ands or buts about it)
You will learn shime waza<chokes me up just to think about it
You will learn mat holds, locks, escapes, reverses, and combinations, as well as how to transition from standing to the ma in many more ways than one:-).
Yes, if you stay long enough or they teach self defense judo, you will learn how to combine striking and kicking and defenses against all of these with your grappling waza. Some may not know this, but Judo even has defenses against karate techniques built into one of their kat, actually several.
You may learn Judo kata, done with two people.
You may go into tournament or not if you please, but you will learn to practice randori, Judo free play, very important.
All this and more you will and should greatly enjoy learning.
If then you wish to take Aikido(Yoshinkan or Tomiki guys actually CAN fight), r a good Jiujitsu style from a good teacher(JJ and BJJ are fads again now, so lots of substandard teaching is out there.)Good Judo is good Judo.Obviously if you can tke BJJ or NJJ with Mike or Joe or someone good you know, that would be great.Very few frauds in Judo these days though.Any such would be most quickly spotted first time kumi kata occured(taking hold of lapel and sleeve.)
Any competent green belt or above Judoka can tell just from holding the other's i, if they know any Judo or not. Here's a clue:If you suddenly and repeatedly wind up smoothly on the mat, they know.
Here's a clue that they don't. If you are a good white belt, and every throw you try works , and the other guy has a Black Belt on, they didn't earn it.
It isn't like karate where the refereee doesn't see the point, and then does as your opponent throws a punch six inches from you and scores.
It is like this: You grab on, he grabs on, hajime, and someone goes head over applecart onto the mat, Ippon!That's in a mismatched case. Now beteen two equally matched judoka, it can look boring, nothing is happening, but it doesn't feel boring.
First one tomake an error , first one to mistake, and they get dumped.
Take one of those same judoa, put him with a karateka knowing nly how to fall pls say, shodan or so in karate, and grab on, and the karate guy gets to practice all his falls.
In Judo this is known among the older players, as 'Fresh Meat."