orderBy(\DB::Raw('case when avatar_id = 0 then 0 else 1 end'))

Doctor::join('users', 'doctors.user_id', '=', 'users.id')
            ->with('user')
            ->withCount('services', 'notebooks')
            ->orderByDesc('notebooks_count')
            ->orderByDesc('services_count')
            ->orderBy(\DB::Raw('case when avatar_id is null then 0 else 1 end'))
            ->where('status', 1);