Interesting question.
La Liga is definitely not my favourite simply because Barca & Real are way, way better than all the other teams. It's just not that interesting.
Serie A is another league I don't really enjoy. I personally don't like the tactics small Italian teams use such as using a completely rigit and defensive game plan when playing better teams.
Then there's Ligue 1. It's certainly getting more and more interesting but it's not for me, at least for now.
So, we are left with the Premier League and the Bundesliga. Both are entertaining in terms of goals scored etc although the Bundesliga can be more surprising as more teams fight for the league every year(at least in the last decade). I think I'll vote for the EPL, though simply because it's the most talented league by far.
That being said, I watch all of the league above at times, I just don't enjoy them as much as the EPL and the Bundesliga