They’re both nice. However, words can be used to express how you feel about them the 2nd one.
Which one would you by for yourself?
You know them, then you know which is more their personal style.
Maybe ask each of them which one they’d by for the other or another person that they both know. That will tell you which one they like or confirm your choice for them.
The bottom one. I don't wear a ton of jewelry in general but I'm not a monogram person. Especially if you have single BM that might get married soon so their initials will change.