But, as for Leela... I must agree. I really liked her. But I wouldn't say "dumb" there.
Perhaps, uneducated? Naive? Whichever, she was a good foil and companion for the Doctor. And savage too.
Strangely, although Troughton is my favourite Doctor, nearly all my favourite stories are from the Pertwee and Tom Baker years.
I forgot about my least favourite companions: Rose; Nyssa; Adric; Thurlough; and, Sarah-Jane. I'd put Peri in there too, but she had ... attributes.
Second best villain: Davros. The rest aren't even close.