Since I only watch the original, that's all I can comment on here:
There's no other choice for me -
Marg Helgenberger deserves any accolade that would come her way. The way she's turned Catherine into such a multi-dimensional character is a great testament to her acting. Even those who hate all of the Cath!Drama have to admit that she does an excellent job with the scripts that she's given. Take for example the latest episode Law of Gravity, where she's crying over the death of Mike Keppler, or her wonderful performances in BTK 1&2, or how about the emotional wringer her character went through in Lady Heather's Box? Or maybe just something as simple as driving a car real fast in Revenge is..., where she gets out of the car and does her own cute ad lib of "thank you, good night". For those that don't care for Catherine because she gets all of the "highly dramatic" parts - ask yourself why TPTB keep giving those types of scripts to her character. It's because Marg can knock them out of the park with little effort.
Now, if there would be an award for "best supporting CSI character" - one who is a big part of the show, but small in terms of screen time, - It would be hard for me to choose between Louise Lombard, Eric Szmanda or Paul Guilfoyle.
Louise's character of Sofia being the newest, has gone through major changes - from a dayshift CSI demoted to grave, then brought back in the role of a detective (which I think the character has finally found her niche). But Louise would get a vote from me just for the fact that she has to do her entire character with a different accent from her own. That can't be easy to have to concentrate on not only the acting, but the accent as well.
Eric's character of Greg has taken emotional turns. With the work he's been given, Eric has done a great job - even though I think the character has taken a step backward. They've taken away his fun-loving attitude for a more quiet, studious CSI who now has personal drama.
Paul's character of Brass has probably been the one constant the show has had from the beginning. I wasn't pleased with his character's extremely gruff behavior in the first few episodes of the series, but grew to like the character since TPTB have come to rely on him for sarcasm, as well as Brass not knowing the full ins & outs of forensics so the CSIs have to explain to him (as well as the audience).
As a fan of Jorja Fox, I wish I could say that I'd put her in some category for an award, but I can't. Her character of Sara really hasn't given her the opportunity to show even a fraction of the acting she's capable of. There were a few small glimpses of it - such as in Nesting Dolls, Too tough to die, or committed- but those are few & far between.