For instance if I ask questions concerning how good is a training program compared to others etc...
Is it allowed?
It wouldn't be allowed if you asked it like that, as it's just pure opinion.
What would be allowed, and I'd certainly encourage it, would be if you asked what training programs are most effective towards a particular goal that you have.
Something like this is certainly answerable in my book:
Is StrongLifts better than German Volume Training if I'm primarily interested in getting a body builder's physique?
There are opinions involved to some extent, but there are fairly concrete results from different programs targeted towards specific results.