Hey Nas
I use three nikon prime lenses. 28mm f 2.8, 35mm  f2 and 50mm f1.8  but most of time 35 mm is my workhorse. I think you have pretty good sense of light watching your videos. I just do trial and errors to learn about light and I still have not learned 10 percent about light yet. It is as mysterious as women eh.
I work more with natural lights but I had always wanted to learn about using strobes. Maybe someday I will.
If you ask me, I wouldn't suggest you to go that wide, unless u are really into wide angles. I think 20 mm converst to 35-37 mm for Canon after considering cropping factor.so it might be ok too. It depends on what u want.
But what about 35mm lens?--> http://www.bhphotovideo.com/c/product/12119-GREY/Canon_2507A002_Wide_Angle_EF_35mm.html
It would convert to roughly 50 mm which is what our normal eyes see.
I also sold all of my digital gears and shooting all analog these days. But I plan to get Canon 5d mark ii or new nikon full frame camera if they release by end of year if i can save enough which I am not sure.
Cheers.