I've been on and off my Xbox One controller over the years. Like what Pepi said, a keyboard without NKRO actually handicaps you into being unable to deathbomb in certain situations, so, without my mechanical keyboard, I would've probably stuck to the controller.
To me, the main issue with a controller is precision. Light taps and movement adjustments require a lot more restraint to do with a stick than with static keys.¹
On the other hand, a stick gives you a lot more freedom of movement, and I greatly enjoyed the perks it gave in the likes of Deathsmiles, Dariusburst and so on.²
Generally, I've found controllers to have helped my game sense, and afterwards, my gameplay with a keyboard improved as a result, since my brain started considering more complex pattern dodging paths than when I was exclusively conditioned to keyboard inputs. Although how much of that was actually due to experimentation and how much is just practice/rote learning up to anyone's guess.
With my experimentation phase over, I mostly stick with the keyboard now. Still, I will move over to using a controller if a mechanical keyboard is not available or if my old hands are already giving me a prescribed dosage of joint pain, a result of the many micro inputs required in an extended play session.
Little bonus fact: I had a similar journey with fighting games. While I used fighting game sticks/xbox 360 controllers in my early masher years, I moved from using the stick to eventually being fonder of the precise inputs of a keyboard. I can say that safely hasn't stopped me from sucking, but at least I suck while pretending to know what I'm doing now.
Image credit: baalbuddy over at https://twitter.com/baalbuddy
¹ I will not consider the usage of a d-pad here, mostly because as far as an xbox controller goes, using a d-pad is very analogous to the keyboard. I am not sure if the pad in the PS4 dualshock is any better, but it is a popular choice for fighting game players.
² Old touhou games are actually not included here, since the way the game interprets movement inputs is very static. I don't remember if this trend is kept with the newer titles.