I'm using Paragon NTFS.
I tested Paragon using its time-limited-fully-functional trial period, and then ultimately paid the $20 to keep using it. I wanted to create an "upstairs" Mac mirror of my "downstairs" PC video library, both to serve as a backup and to create an "upstairs" video server. The easiest way to do it, and to have the "upstairs" drive fully functional in the event of a "downstairs" failure was to use NTFS on the "upstairs" drive. (I keep them synced over our home network.) With Paragon installed, NTFS formatting and use is transparent and native-feeling. I ran a few benchmarking tools before I put the drive into service, and I found no difference in speed between native HFS+ and Paragon NTFS formats used on that volume.
If you just want to use NTFS briefly to copy files over, OS X can read NTFS, but the volumes are read-only. If you just need a brief transition period, Paragon's free trial will give you a couple of weeks.