Congrats! I was also accepted to Union today! I spoke with admission reps at Marian several times and strongly considered applying there. I decided not to though, because all of their lectures are online. From what I understand, the only time you meet with professors or classmates face-to-face is for clinicals. While it is convenient to have the lectures online at times that work for you, I prefer classroom interaction and the ability to build relationships. I just think so much learning comes from that itself.
I also considered NCLEX pass rates. Union's NCLEX pass rate was 96% in 2017, whereas Marian's was 89%.
Marian requires more pre-reqs than Union (Chemisty and two theology courses). It is also significantly more expensive once you matriculate. If the tuition rates posted are accurate, Marian's tuition for the program is $51,975 and Union's is $37,485.
Have you visited the area? Marian's "campus" is located inside Saint Thomas West (a hospital), which is a nice area of Nashville, but cost of living in that area is higher than where Union is located in Hendersonville. Hendersonville is is a cute suburb and not far from Nashville.