Honestly, only watch if you wanna get some good laughs out of the fiesta games that happen there. If you want to watch real competition, watch LCK. That's the really strong teams who know what they're doing. EU and NA are just way too bad, with EU being slightly better than NA. Most players there are no-namer challengers and like it or not, EU and NA challenger are easy to achieve if you put time and effort into the game, while Korean challenger is actually hard.
Teams in NA specifically don't really care. Most players go there for the money, and most teams don't care, because they know they have their spot in the league. Free money. It's all about money and exposure there, whereas in Korea, they do care as a tradition.
What I do is I watch LCK full games, and I try to watch all teams, even the lower ranked ones. For NA or EU, I only watch the highlights on Youtube mostly to pass time. It's very rare if I watch a full game, and that's probably something like FNC vs G2, and maybe just the finals or something. Anything else is just random clown fiesta crap.