Sam annoys me - but that is because I hate the trope of the scientist who can do anything in any sort of science despite whatever is said about their specialism... and it is a trope that Stargate uses all the time. Dr Fraiser is good, but doesn't really get any character development or plots. Dr Weir - I agree she is good to start with, but the further along the show goes, the worse she gets as a character.

I'm very bad at judging acting.

I'm not surprised that you don't like him :)
I just ignore the casting - it is the typical thing that every female character (especially the more they are in a show) has to be good looking or better. (Even most character that are referred to within shows as ugly or whatever are far above average) /end bit of rant - I suspect that I've ranted at you about this before :)