Are full squats with less weight a better muscle builder than parallel squats with more weight?
You would get different schools of thought here and I know people that prefer one more than the other ,
Personally I prefer deep squats but I'll say include both in your program if you can perform deep squats with the right technique / posture .
To answer your question full squats are a better overall muscle builder IMO cause you are working on greater ROM, ofc greater ROM normally means less weight.
However if you targeting specific muscles I.e your hamstrings then the parallel would make sense as well.
Again i am not going to discuss about optimum angles / compression forces on relevant joints and what squat is better over the other because that's not what you are asking and I am sure is covered in another question.