Yelm often gets a short-shrift by many fans. But the Sun God is one of the Great Gods of Glorantha, with oodles of Rune spells, subcults, and more associated gods than you can shake a stick at.In Dragon Pass, his cult is the preserve of the Pure Horse People aka the Grazeland Pony Breeders.
In Peloria, his cult is far more pervasive, and is part of the state religion of the Lunar Empire. The Lunar allied nation of the Char’Un are also Pure Horse People and worship Yelm. And the Pure Horse People of Pent also follow Yelm.
Even the Orlanthi acknowledge the importance of the Sun, and he is invoked in Ernalda rituals. He doesn’t have a cult among the Orlanthi (they prefer Yelmalio, whom they find more useful and helpful), as he is a distant god, stuck in his ways. But they definitely acknowledge him.
So I ask you, who loves the Sun? Well just about everyone. Except the trolls. They hate him.