Different churches draw different personalities. There's differences in doctrine, worship style, race, and class. There's also personality differences. This is true for Protestant denominations. Methodists, Baptists, Episcopalians, Presbyterians, Lutherans, Pentecostals, Church of Christ, etc. draw people with different attitudes and personal habits. If you drink alcohol, you're gonna join the Episcopal or Lutheran churches. If you're dead set against drinking, you're gonna join the Baptists. If some Baptists are intolerant toward alcohol, some Episcopalians are intolerant toward people who don't drink. It also depends on how much you care about the creeds. Many Episcopalians say the Nicene Creed every week but don't believe it. I like the Methodists because they have both the fundamentalist nutcases and the extreme liberal nutcases. I'd rather have both than just one.
Converts go to whatever group attracts their personality. It's more reliable than what is or isn't true. I don't drink or smoke and I'm a semi health nut, so I'm a good target for the Latter Day Saints. On the other hand, I admire Catholic Social Teaching and I like liturgy. Catholics are pretty open to all personalities, but a lot of Catholic converts are a certain type of person. The Young Fogey. The fan of GK Chesterton, CS Lewis, George MacDonald, etc. The medievalist. The history nut. They're in some Protestant churches but they're a dwindling minority. Protestantism has little to do with church history any more. It's sad.
It may work for other religions too. Most Wiccans are bisexual goth women. Not all, but most. I was interested in Orthodox Judaism for a while. I liked the strict rules. I don't know much about Islam, Hinduism, Buddhism, etc. In the US Buddhism draws the same kind of people who become liberal Christians.
A lot of people deconvert from religion altogether. Most people here are raised in religion so most agnostics and atheists are converts. There's a difference between agnostics and atheists. Atheists are sure there's no God, but agnostics aren't. This is mainly a personality difference. If fundamentalist Christians deconvert they become atheists. If the more tolerant kind deconvert they become agnostics. Agnostics are more laid back than atheists.