I started in NICU as a new grad, and went to an LDRP unit after about 5 years. I looked forward to the L&D portion of orientation, as I was a bit of a high-tech junkie. Much to my surprise, I found that I loved post-partum/mother-baby, and that L&D was "OK", but not the "rush" I expected it to be. About a year later, hubby was transferred, and when I looked for a new job, I returned to my "home" in the NICU.
I suspect that you will favor the unit you go to first. It is simply a matter of having familiarity and a greater comfort level in what you learn first. Starting in L&D can be overwhelming, especially in an LDRP unit where you will be responsible for the care of high-risk ante-partum moms, laboring patients, post-partum moms and babies, C-section moms (both in the OR and post-op), and recovery of post C-section patients. You will probably be required to obtain fetal monitoring certification, NRP, and possibly ACLS as well. That is a lot to accomplish in the first year or so after graduating!
At least in NICU, your patients are all babies. Silly as that may sound, it places some limits on your scope of practice, and on the certifications you will be required to obtain.
Both areas are incredibly challenging and rewarding, and I wish you the best in whatever you decide. There are very few nurses who are competent in both areas. If you choose to pursue both you will eventually be well-positioned for transport, education, or administration.