That is a no brainer.
Horner!
By a wide margin (DiLuca for example looked like Kindergarten style in comparison, even LA in his "best" times can´t come close to this).
The most outright blatant cheating I've ever seen, in any olympic sport, anywhere in the world, in my whole life.
Unprecedented how a 42 year old over-the-hill injured rider rode away on one leg, always out of the saddle, from his young talented favoured competitors*.
Horner seriously took the p!ss out of all of us with his Vuelta performances not only in one, but every mountain stage.
The biggest mutant performance of the past 150 years in cycling.
A complete Vuelta annihilation. It was no easy task given the past of the many many doped and suspiciouss Vuelta performances.
* = What makes Horner even more sickening are the facts, (a) he was a failure in a 2nd tier team his first time around in europe. He was so bad he simply didn´t got a new contract when reaching his peak age. And now in grandpa age, he was breaking doping records of the darkest cycling era with ease.
(b) After the AC positive, there was a small window where riders may have thought twice before doping big time again. Now Horner showed every young rider their only chance is to cheat again. Basically he destroyed a whole promising young generation. He single-handedly closed the window.
His final stunt was to led testers look like fools, yet everybody knows he was hiding from them. He spat everyone in the face. The most disgusting person in cycling. LA was/is an angel in comparison.