Earthshock, Arc of Infinity and Snakedance (Fifth Doctor).
Three excellent serials.
First time I've seen Arc of Infinity called excellent!
I do enjoy it though.
My criteria for rating television shows are pretty simple. After I've watched it, do I feel like I wasted my time? Arc of Infinity kept my attention and therefore it was excellent. Omega is an interesting character, one I'd like to see more of in modern Who. That said, I can understand why others wouldn't like it all that much. It drags here and there and the ending doesn't make much sense.