If YouTubers had to voice Undertale Characters, here is who I'd pick!:
Sans: Djsmell
Papyrus: Jacksepticeye
Burgerpants: JonTron
Mettaton: Markiplier
Flowey: Thomas Sanders (for obvious reasons)
Alphys: UndertalePeasant
Undyne: SSSniperWolf
Toriel: CypherDen
Asgore: Starbot Dubs
Asriel: Skeleton08
Gaster: DryeGuy
Frisk: Thea (from Crainer and Thea gaming
Chara: Sr. Pelo
Ice cream bunny: ChromaDust