Oh god damn is Pamela Salem seriously sexy! It's her voice as well. She is a shinning example of why English women can be the sexiest.
I think that maybe the best recurring guest actor is Michael Wisher to be fair, as his performance in Genesis as Davros is possibly the best of any guest actor in the entire series.
I also like David Banks as the Cyber Leader, the guy who played the Ice Warriors different commanders in Seeds of Death, Curse and Monster of Peladon (Can't remember his name.) Kevin Lindsay was also exceptionally brilliant as Link and Styre. I'm not so keen on his character in Planet of the Spiders, but to be fair that whole story is shit.
Stephen Thorne also deserves credit for Azal and Omega. Everybody seems to hate his Omega these days though? I don't get it? I loved his performance, the bit where has a break down and the world shakes, whilst OTT is marvellous.
Kevin Stoney also deserves a shout out for Mavic Chen and Tobais Vaughn, two very memorable human villains who helped lay the template for other Quisling type bad guys in the series.
Also Bernard Horsefall played three very different types of characters, the comic relief in Mind Robber, dashing hero in Planet of the Daleks and the villain in Deadly Assassin, and he shone in all 3.
I'd love to include Paul Darrow Rushy, but I'm not sure you could say his performance in Timelash is good LOL, though it's certainly incredibly entertaining.