Ray had his flaws, but there is a tendency to compare Ray's not-so-likeable actions with his better self.
He was still far more ethical overall, in general, than others on the show
Ray does deserve some empathy, I think.
Grew up without the most supportive Father,
Garnet McGee with JR - losing her to the rich Ewing, who he thought was a friend
after Pam left him for the other rich Ewing. It would certainly not be pleasant for him.
Didn't have access to the Ewing wealth until later
Found out later that Jock was his Father,
Not as business savvy as his brothers, or his wife. It was only human that he would have some resentments.
"Conundrum" made an interesting point that Ray was not wealthy, but happier, if he never knew that he was a Ewing
Even when giving Bobby some help in the battle for Ewing Oil, it ended in disaster.
JR rightly pointed out that Ray had to take some responsibility for getting involved.
A hard truth, but still the truth
Again, he had flaws, but nowhere near most of the others.