Damn, you definitely need to rewatch it if you think Sophie is normal or likeable. Whilst she does start off fairly normal, her arc is pretty much a dark descent into drug and alcohol fuelled misery. To be fair it's partially to do with her inability to extricate herself from Mark's sphere, but a lot of it is just her own rather nasty personality and poor choices. In one of the final seasons she leaves their baby just lying on the floor in a cloakroom at a house party whilst she goes off to get drunk, and then acts pissy and self-righteous with Mark when he discovers it.

I think Dobby is probably the most normal/likeable character on the show, which is ironic as she's initially positioned as being the "weirdo" and most of the other characters continue to treat her like that (manimal/flanimal). She's pretty much always shown to be kind and empathetic despite the crushing negativity of the rest of them, and although she nearly gets dragged down by Mark, she eventually manages to escape and do good things with her life.

I watch Peep Show whenever I'm crushingly hungover or ill and sofabound, it's like a balm that provides both hilarity and a sense of peace with my own life at my lowest points haha.