What about Catholicism appeals to you? At lease moreso than other religions?
For starters I choose to be Christian because of the message of Jesus. I find this to be a message that does not rely, whatsoever, on the existence of the divine or metaphysical to still have vast importance on day to day life and personal ethics.
That isn't to say that I don't find Buddhism quite attractive, I do, but, for me, the appeal of Buddhism does not begin as close to the reality of everyday life as does the basic tenets Christianity. So with that, I would opt for Christianity as a choice.
From there, well, Catholicism is Christianity at it's root. The appeal is in the adherence to traditions and dogmatic principles that have existed for thousands of years.
Compared to Protestantism, I think many of the original Reformation created churches are fine; in fact, many of them are in communion with the Catholic Church since their fundamental teachings and beliefs are so similar.
Christian religions that stemmed from the partition of the Roman Empire, and the Great Schism are also largely in communion with the Roman Catholic Church and are considered part of the Universal Church. So this would include all of Orthodox Christianity.
I've studied, extensively, Gnosticism and ancient Christian mysticism and find the belief system and the historical derivation of their practices and ideology fascinating. I don't think one can even begin to understand Christianity in a complete sense without understanding these religions.
Now, with respect to "Evangelical" Christian Churches, well, I'm sure many of their attendees are good people. But I find many congregational Christian religions ultimately lose their way since they've divorced themselves from tradition, from the authority of the Church, it's wisdom, and instead opted for a personal, individual interpretation of the Bible.
I find this leads, almost invariably, to irreconcilable conflicts and contradictions and this causes too many people to lose their faith due the disorganization and almost make-it-up-as-you-go attitude about scripture.
I don't mean to sound like a Catholic apologist, but, that's my rational reason for being a Catholic; given that I choose to be a Christian, Catholicism at least seems like the most logical choice.
Why do you believe god exists?
That's complicated. But can be summed up by saying, personal experience.
What is it in the form of, if any?
I have no idea and wouldn't venture to guess a conclusive statement.
I would say though that I believe that God might not be a "person." God might simply
be the multiverse/universe. And the Universe might fulfill what we as people feel would be the requirements for a God.
There are lots of answers to that question.