Is Starku worth using?
Yes, if you need Mythic damage now. Pro Game Guides places Starku A and Beebom S+, and both describe the same thing: strong damage for the rarity and a powerful nuke. He is the straightforward answer to 'which Mythic actually kills things' — unlike utility Mythics (Goju, Bluma), his entire documented value is burst.
Tier placements are the two public tier lists (Pro Game Guides and Beebom), shown side by side because they disagree on several units — see the full tier list for how we handle conflicts.