I like both
Mary and
Marie. They're both unusual by themselves nowadays, but perhaps
Marie would be a little more refreshing as a fn, considering it's so often used as a mn right now. I think the same could be said of double names too, but in that case the choice of
Mary or
Marie would depend somewhat more on the second name's sound and how the double name sounds as a whole.
Michaela isn't inherently trashy; neither is
Mikayla. They were given the connotation of trahiness by ignorant people who don't know how to spell--or use an ethnic name properly, as in
Mikayla's case (
Mikayla's the Ukrainian feminine form of
Michael, and perfectly legit, despite perceptions to the contrary).
I wouldn't say
Michaela's trendy, because it's a reasonably classic name imo despite its use being concentrated in modern times. It
is extremely popular today, however, and maybe
Michelle or Michèle (but not
Michele, which is masculine) would be a better, more original choice today.
Miranda