I'd like to offer one reason, based on my own experience: love.
Why be a Catholic? It helps you to love. It certainly helped me to love.
Obviously not my friends and family and those I admire; I loved them already. But the other sort. The inconsiderate and unkind, selfish and hateful, the criminal, politicians of ill will... the list goes on but you get the idea.
Loving people who are unloveable is a freeing experience. No more being bound by negative and potentially self-destructive emotions. Recognition of God's love for me despite my many faults. Immersion in the most beautiful state of being one could ask for.
But how can I love someone like, say, the cyclist who cuts me up on the pavement or, rather more seriously, the likes of Donald Trump or Vladimir Putin? Loving is not the same as liking. I don't have to like them. Part of what loving is, is recognising that these people are (a) children of God (b) broken just like I am, perhaps more, perhaps less, but still broken (c) broken children for whom Jesus died in order to heal just like He died in order to heal me (d) capable of holiness if they choose to repent.
The above is not the full story but it is a part of it and it is what is in my mind and heart to write here.
Of course, the Catholic Church has certain beliefs that many people find unloving. For example, her teachings regarding sexuality. I'll try and come back to this because I have skin that game: I'm bisexual. For this post, though, I am so happy that I became a Catholic. In doing so I said yes, a mighty yes that even Mr. Emerson might have been impressed by, to love.

