Is HOTS better than league?

HOTS is a team game, LOL is a single player game you play on a team. HOTS has a bigger barrier for winning at higher levels, if you do not have a premade, you are going to have a generally harder time compared to LOL at comparisons of the same skill level of a single player.

Is Hots more fun than LoL?

Hots has much more interesting gameplay while league has only jungle and laning. Some may find them both fun, some may hate laning, some may hate jungling.