Dude I have played so much Vladimir. I have since diversified but I still remember the good old days.
I played Garen up to level 30 4 seasons ago and then switched to playing Vladimir. It was literally Vladimir 24/7 for months and months perhaps even a whole year. The whole doctrine was "flawed" (full AP with Will of Ancients into Deathcap rush, no CDR emphasis, simply target what you could hit like an ADC) BUT IT WAS FUN AS HELL.
By the time of the Vladimir Rework I played a bunch of other champions but Vladimir was still a mainstay pick. Went back into playing Vladimir and experimented with everything from full health to tank to full AP. Settled for a build with SV, Zhonyas into full CDR AP and for a while this build combined with the new Burst-the-Backline. I remember EVENTUALLY working Protobelt into the build (I remember it being a HUGE challenge to play this new Vladimir with a Proto active, Zhonyas, active, Ghost, and the new wonky charge E but it was hugely rewarding when mastered). I believe this was the Vladimir High Point (when his E did massive health damage).
Eventually it got nerfed down and as it did I changed the play style and build to include more AP and less health. The 0.8 E nerf is harsh but he still remains in the pool.
Nowadays I like to play with Aerys instead of Electrocute with Lifesteal secondaries (stronger laning, less clunky) while going for a semi AP-focused build.
Something like:
(Ionian) Protobelt > Codex > Deathcap > Void Staff > Rylais/Morello/Lyandries (finish Codes into Zhonyas/Banshees at a strategic moment)
The defensive variation of that is straight Zhonyas/Banshees second damage item
...
I have no idea what awaits Vladimir in the future.