I prefer [name_f]Merryn[/name_f] (and that is how I would spell it, the only other way being [name_u]Mirin[/name_u]) but it is a boys name, or at least is traditionally a boys name. It’s a Cornish/Welsh Saints name and as such could never give it to a girl.
I’m not a huge fan of [name_f]Marin[/name_f], something about the Ma sound at the start. Also, it would be mispronounced as Ma-rin (the a as in hat) I fear.
Almost. [name_f]Merryn[/name_f] was indeed a man; a Welsh missionary who became a Cornish saint. But Meryn and [name_f]Merryn[/name_f] are the only accepted spellings I know of. [name_u]Mirin[/name_u] was a different person (Irish I believe). I wouldn’t give it to a girl either as I know a [name_f]Merryn[/name_f] and he’s very definitely a boy
I would pronounce [name_f]Marin[/name_f] as MAH-rin (ah like cat) rather than your pronunciation, OP (mah-REEN?) There may be confusion, thus I like [name_f]Merryn[/name_f] more. I do like [name_f]Marina[/name_f] though.
Pronunciation-wise, I like [name_f]Merryn[/name_f] better. However, [name_f]Merryn[/name_f] makes my brain go weird - it wants to say “merry” (as in “[name_f]Merry[/name_f] [name_u]Christmas[/name_u])”, but then it tacks on the ‘n’ on the end, so it’s kind of like, “[name_f]Mary[/name_f]-Enn.” [name_u]Marian[/name_u]. I much prefer the spelling [name_f]Maren[/name_f]. Makes things a lot simpler.
I prefer option 3, [name_f]Maren[/name_f] (mare-in). [name_f]Merryn[/name_f] makes me want to say merr-in and [name_f]Marin[/name_f] is muh-rin to me (like [name_f]Marin[/name_f] County in [name_u]California[/name_u]).