I played union at school in northern ireland and had never heard of rugby league until I was something like 23/24 years old.
I watched a few challenge cup matches on BBC, initially without a clue about what was going on. What got me hooked on league, was the way that Wigan, saints etc would pass the ball 8 or 9 times before a break in play. In union, the crowd applauded if they strung two passes together. League simplified play to good passing, good tackling, good attacking, scary aggression, non stop play.
I have always found union boring ever since. And I know it, understand it, get all the subtleties and nuances, but it is just too slow and repetitive.
Ravenhill, home of ulster RU, remains my favourite rugby crowd, and a fantastic match day experience, but there is no sport on this planet like rugby league. I love it.