In deck "the-song-of-rebirth" (https://ringsdb.com/decklist/view/2452/the-song-of-rebirth-1.0 ),the builder use Warden of Annúminas just for its 2 attack. So it's hard to find ally with high attack. So Rider of Rohan is perfect for mono spirit deck:they can quest or attack and can do both with a small limit. spirit side quest is not bad,I'd like to add them to my deck.Totally worth it.

But if my deck don't have other attacker or defender, Rider of Rohan is more like a 3 cost 2 willpower, I'd like to use Galadriel's Handmaiden or some thing else rather than this ally.

Fine stats on an ally, only if you have completed a side quest. Not so amazing as to be worth playing side quests for, but if you already have a plan to get one done early, worth looking to this card. Also a solid card for a Rohan deck, although again not amazing. 3 cost on an ally is significant, and most should pack more punch than this. That said, if it fits the deck it's a solid filler.

On first glance this ally doesn't quite cut it at 3 cost. However pair him with his in trait king Théoden and Thurindir for access to lore without Doomed in Rohan and suddenly he looks rather playable. Questing is one of the traits specialities and for a small price this guy can provide massive action advantage. He's in the right sphere and has the Scout trait which can mean something these days. I'd be hard pressed to leave home without him in most Rohan decks. A solid card.