If you're even somewhat serious about this, I highly recommend Krav Maga, Systema, Escrima and other armed martial arts, providing that you're able to access the real deal and not just a watered down pyjama party some/most commercial variations of them are.
I started with judo in the 70's, switched over to Tae Kwon Do in the 80's Choy Li Fut Kung Fu in early 90's and only when I found (military) Krav Maga in late 90's I realized that training with no rules whatsoever is the way to go. It's brutal, during the first year I broke ribs twice and injuries are not uncommon. On the other hand you train a lot with knives, batons, improvised weapons and guns, including disarming techniques of armed assailants and a holistic behavioral techniques when approached, how to avoid situations and so on.
Later on there's a lot of controversial stuff, including techniques to turn a slung/non-slung SMG of an armed guard against him when you're stopped to verify your ID, advanced distraction methods and so on.
Intense but a lot of fun. It's quite understandable that most commercial training facilities never go nearly this far.
You definitely have experience in this kind of thing, that's for sure.
I am fairly serious about learning some "martial arts" for a few different reasons:
Personal Fitness
Self Defense
Community
Fun/Interesting to learn
I am
not interested in picking up injuries. At all.
The things I do for work or for fun cannot afford serious injuries. Not only that, picking up an injury means no training. At this early stage of my training, gaps forced by injuries would set me back pretty good.
I recognize that systems like Krav Maga are great and incorporate the tools I will likely have with me at the time of self defense, but I cannot practice those techniques, at 100% on another person.
I can go as hard as I want in BJJ without an overly extreme risk of injuries to myself or my training partner.
To me, It's a lot like how USPSA isn't "realistic training" for defensive shooting, but it sure as heck makes you a better shooter, incorporates speed/stress, and you can practice it as often as you like without risks to anyone.
I do plan to compete in no gi BJJ at least a few times when I have enough understanding/experience under my belt.
At some point down the road, it would be interesting to dabble in Krav and other systems, but for now, I am learning the absolute basics of "martial arts" and a new (to me) "combat sport."