First, there are numerous threads around these parts in regards to choosing/finding a quality/legit training center. So, I'd scroll through a couple pages of the forum if I were you and you're almost certain to find at least a couple that will answer most of your questions.
Since I'm on my phone though and pasting links to threads into this thread isn't as easy as if I were at home on my PC, what I'll say is:
1) it depends on what you have available to you in your general area (or within your realistic driving radius). We might be able to direct you to incredible training systems or locations, but if those options aren't within reasonable commuting distance for you it does you no good
2) the instructor matters as much (if not more) than the style in many cases. That said there are systems which in general tend to be more legitimate across the board and others which unfortunately have earned poor reputations
3) your background and the area you live in. If you reside in a very rough area then (modern) weapons and multiples training should be part of what you look for. If you live in a safer, less crime ridden area, then you may not need to worry about such things as much. Then again, if you come from a rougher up bringing then you may have prior experience with weapons anyway.
If you wanted a "perfect" RMA (Reality Martial Art), then it would teach:
-full body effective striking skills
-effective grappling skills (both standing and grounded)
-legal and more realities of combat and strategies to deal with them
-psychological conditioning/stress inoculation training
-verbal self defense skills
-postural self defense skills
-defense and deployment against weapons
-tactics for dealing with multiple attackers
-tactics vs surprise attacks/ambushes
-environmental awareness and adjustments
-use and defense against "dirty" tactics such as biting, eye attacks, etc...
-awareness and prevention skills to avoid trouble before it has a chance to really develop
Whether you can actually find such an art is another matter.