Who is your favorite spanking model or actress?

Still Kami Robertson and even as a Spanker now rather than a spankee, she is still gorgeous!
*Swoons

Amber pixie wells, nice as a spankee but totally magic as a spanker. Would love to see her in an f/m role!

Off topic:
Spankedjenny
I've been disconnected from the life for a little while, but last I heard, Ms Wells had a younger fem partner who she was trying to start a business with (I lived 15 miles away from her at the time and didn't know it). That sort of went belly up, and I think Ms Wells was simply looking to settle down in her life. I don't think she was outed as she posted her address and how to contact her on her blog.
However, things might have changed since then.

On topic:
Merle Michaels holds a special place in my heart for being the first adult woman I saw get a bare bottom spanking to make me think "oh my god, if only more women were like her!"
Erica Boyer only did two scenes that I know about, and didn't get anywhere near a roasting, but that girl could paint a lead in to a spanking scene!
Kym Wilde (Why? Persona)
Flame most but not all with Kym Wilde (Why? physical attributes and her tomboy-like attitude)
Kailee Robinson (Why? she could take a hell of a lickin' and she has what looks like an overbite. Overbites are sexy)
Rosaleen Young (Why? flawless performance leading up to a scene)

In recent years,
Sasha Grey (Why? physical attributes, and attitude)
Amelia Jane Rutherford (Why? flawless performance leading up to a scene)
Ella Hughes (Why? physical attributes and attitude)
Dani Daniels (Why? she could take a hell of a lickin' and ask for more)
Melina Rya (Why? Physical attributes, and attitude)
Ava Harper (Why? Physical attributes and does a fair performance in scene)
Cleo Clementine (Why? Physical attributes mostly)

Latently, I read the OP's posit, and realized I needed to make an extra deposit.
There is a certain genuineness about some who get spanked. To steal from a song "They like it, they love it, they want some more of it." However, being able to take a hell of a bun warming doesn't mean they are a good actress. They are simply doing what comes naturally. Alternatively, some that can play up a scene expertly, can't take more than a couple of smacks before they're done. Alternatively again, some are very relaxed in front of the camera and their personality shines through. Finally, I'm a man, and men are more prone to physical attraction, so I'm not shy to say that's part of my motivation.

However, sometimes the video isn't about the lead in, and just drops you into the heat of the action. There is little to no "Why?" or "How Come?" and you have only the physical performance, and any, if any, dialog to base your judgement.
There's a fair amount of phonies who just take what they can because they're paid more to perform. Is that wrong? hmm...
Sometimes a brilliant and beautiful actress is paired up with a limp-wristed, sissy, submissive, who apparently would be more interested in taking a spanking instead of dishing it out (I'm thinking of one video from Shadowlane).
Sometimes, I suspect it's the "script" the actors are given that spoils a scene. However, some would contend that's the actor's fault, too.

I yearn for an actress who gets her panties lowered only to yelp "oh, does it have to be on my bare bum?" In some 30 years, with countless actresses who are "forced to take some firm discipline," most just become a cow while spanked. They don't exhibit any spirit (perhaps because laws are in place that they can't resist too much, or it looks like they are really non-consenting to what's going on).

And now you know why I try to answer briefly. If you ask for reasons, I'll give you War and Peace.

Erica Scott. She is beautiful and I love her personality.

Princess Kelley May, Stephen Lewis, Alex Reynolds and Paul Kennedy. The former two are just such lovely people (I was fortunate enough to meet them at a party and be spanked by both) and brilliant actors to boot. Kelley's bottom is also just INCREDIBLE. Alex Reynolds was one of the first spanking models I knew by name as a young spanko seeking out content and I've always loved her writing style as well as the sound of her whimpers! Paul is such a firm, imposing top, I really admire him (and also feel slightly terrified of him).

I like Sarah from Realspankings, and Samantha Alexandra. Both are gorgeous.

My favourite on Real Spankings was Holly. She had a wonderful body, an expressive face and she was a real trooper. And she showed it all!