(copied from a post i did on another forum, feel free to ask me any questions about training)
Krav is good at building up aggression and stamina in quite a short time. It can make some people over-confident though I reckon, as the marketing behind it makes it look like you'll be an urban commando within a few lessons. If you can see beyond that then you'll be fine. I would heartily recommend it. It trains scenario based stuff and knives, bats, guns. No matter how many times I have practiced the defenses for these, I still feel like I would poo myself when confronted with them. I have seen some people train who are total rubbish who either can't or won't improve their incredibly sloppy defense, but seem massively confident that they can "handle themselves" amongst a combination of multiple attackers with weapons. Like F*£k. 95% of the people at my place though are balanced individuals who train hard and aren't cocky like that. It's just the odd one.
If I lived in a city or town and had the time, I would like to judo and muay thai. Possibly boxing instead of muay thai, but would prefer the kicking/knees/elbows. Boxing is usually cheap as chips which is obviously good for the wallet, as is judo. Muay Thai is fashionable right now so attracts a premium, also a lot of what is taught is not Muay Thai, apparently. This means you need to look for recommendations for the club you are thinking of joining. Good indicators could be a decent competition history. Does the place churn out winners? MMA places are in vogue at the moment too, so there's probably a lot of **** places (as well as loads of top-notch clubs), so tread careful if you fancied that, and expect to pay through the nose.
There are plenty of "reality based self defense" (rbsd) classes, of which Krav is one of them. A lot of these are utter poo. With Krav, look for IKMF, Krav Maga Global (this is a branch off from KMG, very political, no difference in practice from IKMF except higher level instructors have been instructed themselves more often than IKMF, or something like that). Avoid "Commando Krav Maga" and anything associated with Moni Aizik. This is all based on lies and (proven) false claims about the founder, Moni (e.g. claiming to be ex special forces, swat team and more). You can buy yourself instructor level for a few grand. Other than that, apparently Tony Blauer SPEAR System is good, although I know nothing about it myself.
If you can get yourself a nice mix of striking and grappling, and get the chance to spar you'll be fine. The only other thing I would suggest is avoiding shitholes and knowing when to turn and leg it, to avoid fighting.