I like/have Clannad 2, Dulaman from the '70s, Fuaim & Sirius from the '80s, and Anam from '90. The evolution of their sound from traditional folk/folk-rock to modern is more dramatic than Fairport or Steeleye Span, imo, while maintaining their folk roots. Looks like the 'Best of' has a few from the early days, and the theme from "Last of the Mohicans" is definitely a keeper. 
Thanks man, appreciate the input. I am listening to Amen right now and it is also good. I've actually enjoyed them all so far. I believe this Amen album is one of the ones Enya was a part of, from what I've read, she was only a part of the group for a cuople years before embarking on her solo career, I enjoy some of her stuff too btw which was how I stumbled accross Clannad in the first place.
What you mentioned about how they have managed to keep the "folk" heritage over the years and yet manage to migrate to a more "modern" sound is a common comment in the write ups I've read on them. Kinda cool
