I guess I'll do this tiers thing.
Game-Making (I wouldn't call it breaking) - Fountain of Youth, Uluru, Great Barrier Reef, King Solomon's Mines, Lake Victoria.
Excellent - El Dorado, Sri Pada, Mt. Kilimanjaro, Rock of Gibraltar.
Good - Mt. Sinai, Mt. Kailash, Mt. Fuji, Cerro de Potosi.
I'll take it, I guess - Old Faithful, Baringer Crater.
Nope - Grand Mesa.
What the hell, game, how exactly do you expect me to work that? Why are you so useless! You could have been so good! - Krakatoa.
All of these assume that they've been found at a fairly early stage in the game. Bonuses fall off hard later. Even something like 10gpt, which can be huge early, is not particularly impressive later. The game-making ones are the exception because with the exception of Uluru, I believe they retain their usefulness throughout. FoY is doubly good because you don't actually have to work it to get the happiness, it just has to be within your territory.
ADDENDUM: Asterisk by all of them for Spain, hah. Spain can turn most NW's into game-makers, and anything above 'Good' becomes a game-breaker.