I think there were differences between them - other than being male and female which I am not going discount as a factor in how they were perceived!
Stephen wore his emotions more obviously on his face whereas Rachel had a better poker face. We know that Stephen was struggling emotionally more obviously than Rachel appeared to be.
Also Stephen was a bit more reactive than proactive - Rachel was more actively deceptive in her game play than Stephen. Which made her a brilliant player but I can see why this made her look less likeable.
I also think some of Rachel’s actions have been misinterpreted- I keep seeing “snide” used to describe comments she made which I perceived as more tongue-in-cheek. She herself said on Uncloaked that she was surprised at the reaction to things like the comment to Ross about the turret which was meant to be a joke.
Personally I think Rachel was an incredible game player and I don’t think it’s fair to judge her character on how she played the game. She’s clearly capable of being absolutely formidable but none of us know how she uses that power in her daily life.