League of Legends (LoL) Question: Triforce vs BotRK on Udyr

Trinity Force is more common. Movement speed (passive and on-hit) is very valuable on Udyr. He can also proc Sheen extremely often. I could see BotRK being okay against people like Mundo or Cho'Gath but you might want to get both in those cases.

I'd go with Trinity Force because it gives you movement speed to negate the kiting you'll be facing, sheen passive, movement speed when you hit an enemy, attack speed and health to make you more beefy. I'd probably go neither if I was behind in the early game or if it isn't late game tho.

if you want to go full ad, i dont see why dont get both, if you want only one, i would say Blade of the Ruined King since it gives you more sustain in fights, % damage and a speed boost to get fast to the target and slow it, to escape or just to slow one enemy to save your ally.