A nice gym with pears, paws, makiwaras and other sports equipment.
The main thing is that the coaches are passionate about martial arts and interested in their work.
I've been practicing krav maga in this gym for over a year.
The coach shows all the movements repeatedly, then looks carefully, notices mistakes and corrects them.
Different techniques are given in different training sessions - you won't guess what will happen today, and it's interesting.
He tries to develop students' resilience to stressful situations, so he can be harsh and menacing (which sissies may not like).