As far as mainstream NA porn goes, there's a bunch of really great stars out there.
I'm a huge fan of Wicked's lineup - both current as well as past. Their biggest star -
Jessica Drake - is not my type but I enjoy her performances. Especially since I've seen her in Manhunters. She got a bounty hunter license in preparation for the role and is in fact freelancing as bounty hunter a little.

But I keep having this feeling that she's the Wicked #1 star mostly because she's Brad Armstrong's wife. But yeah, whatever... My two favorite current Wicked stars would definitely be
Kaylani Lei and
Kirsten Price. Kaylani is an amazing performer and Kirsten is stunningly hot in classy and elegant roles (she was a complete miss as a hard-ass bounty hunter in Manhunters though; not her thing for sure.) And I simply love
Carmen Hart - she's an ex-contract star for Wicked, cute little brunette from North Carolina. Very natural.
When it comes to freelancers, I used to like
Eva Angelina a lot, but her stuff got fairly repetitive. At some point here scenes became be very similar to each other and my interest kind of faded. Quite similar in the looks department and seemingly more interesting as a person is
Audrey Bitoni. I've seen/read a bunch of interviews with her and she seems to be a fairly smart young woman. What's interesting is that she claims she has never had an orgasm. Hard to believe. And BTW her lips are natural (boobs aren't, obviously.) I used to like
Jayden Jaymes a lot. She's a solid performer with a spark but learning that she's a complete slob was a huge turnoff for me.
I like
Asa Akira - she's one of the best, active, unforgiving Asian sluts. She likes it rough and I like watching it.

There's another performer I like in the same "category" but with a completely different looks.
Adriana Deville is an amazing hot MILF from Miami, with awesome nipples and a great attitude (she also happens to be one of the most inexpensive pornstar escorts.) I love her "hungry for cock" attitude. Pure gold.

She's got an amazing scene with
Madison Parker (FFM).
I also like
Ashlynn Brooke a lot. She's quite a cutie and I don't even mind her busted boobjob. I think she was the best in her early web appearances. I love the fact that smartass performers/cameramen could not bullshit her and she would respond with pretty witty comebacks. She used to sell cars so I guess she knows hot to outtalk others. She's a New Sensations contact girl now and she's been more involved with production side of the industry than performing these days, which is a bummer. Oh, and I also like
Bobbi Starr. Very smart and talkative medicine student with a pretty long list of BDSM appearances.
And last but not least I simply love
Jessica Jaymes. She's not the brightest bulb in the box, but she comes across as funny, natural and caring about her fans. She's also one of the very few pornstars who have something you would call a consistent image (heavy metal in her case.) With an exception of 2 or 3 scenes where she seems to be uninterested in what she's doing, she's an amazing performer. Very fun to watch.

There's also a long list of mainstream American pornstars I simply can't stand for one reason or another.
Shawna Lenee being an annoying kid she is (although she's a great performer, don't get me wrong.)
Bree Olson for having nothing interesting to say and working as if she was forced.
Amy Reid for being super fake.
So yeah, that's part of my top and bottom lists.