I can't vote because both of my first two 5e characters were multiclassed, and you've only allowed us to pick two choices.
My very first PC was a halfling rogue/bard/sorcerer. I built her using the final Next playtest rules. When we transitioned to using the published 5e rules, I found she didn't quite play the same way due to various changes, so I retired her and brought in a half-elf paladin/fighter who made it all the way to level 20. (We were playing a Next/5e conversion of Age of Worms at the time.)