haha, yeah Betty was one of my favorites, though I don't think Peggy was far behind in terms of acting.
Most of them were really good though, the Mad Men actors had a great knack of portraying their emotions with their mannerisms alone. Nothing ever needed to be spelled out.
Stick with it BW, and then maybe give it a second watch. I stopped watching around S4 or S5 the first time around as I thought it had become dull and, as you say, found all the characters grating. But I loved it the second time around, easily one of my favorite shows.