I dont use either, I dont use any software that I have to have a subscription to or that they make it so expensive that they encourage people to buy a subscription to, make your business to exposed to problems if they go down or want to charge you more.
There are lots of good affiliate software out there you buy buy for just a few hundred dollars thats as good as NATS and MPA.
If you want a URL to what I use shoot me an email
[email protected]