Paragon NTFS for Mac vs Tuxera NTFS for Mac

I bought 1 TB WD My Passport external Hard Drive on which I've copied all files I need form my PC. I'll copy those files to iMac when it arrives (for two weeks) and after that, this external hdd will serve me as a back up disk (but also for file exchange with other PCs and iMacs). External HDD is now formatted in NTFS and I know Mac OS X can read, but can't write on NTFS disks. Which software to use for this purpose?

"Paragon NTFS for Mac" or "Tuxera NTFS for Mac"?
Links:
http://www.paragon-software.com/home/ntfs-mac/
http://www.tuxera.com/products/tuxera-ntfs-for-mac/

Is this software safe for system? Do they cause system instability?

Thanks!