Well, you should just use a variety and cycle them in and out but I get what you are saying about the difference between a walking lunge and a regular dymamic lunge (as opposed to a static split squat or reverse lunge).
If they were the "same" you'd be able to use the same weight for the same volume, but I doubt you can or at least I can't. A "dynamic" lunge is simply going to have more emphais on acceleration than a walking lunge. In order to bring the front leg back to position your have to overcome the weight with some speed. You can't do it slow, hence why they are called dymamic lunges. So in that sense it probably will develop more strength-speed in a functional sense but of course it will contribute to all strength qualities.
This is not to say that walking lunges cannot be used in a similar fashion but they do not necessitate it. That is to say, there exists a weight, given the balance and control, where you can do walking lunges super slo-mo
. Reverse lunges should be the "easiest" after static split squats until you get into elevating one or the other leg and then it's anybody's guess.
I think they are both good and equally useful and I would never say one is better than another.
Not to overcomplicate matters though. Just saying I see where you're coming from. Just use a variety of single leg movements and don't overthink it. And like Andrew said the stride length will help determine how much what part of the legs are worked more. Also, to some extent pushing off your heel or toes.