I want to know what is your opinion about the strongest class for season 23 for clean a mobs

For clearing trash on higher GRs in groups, Heavens Fury Crusader or Bonespear Necro probably.
Depends on the content (rifts, grifts, nephalem rifts etc.) and difficulty and also if you play solo or in groups.

for Gr70-80 it would be hard to be any faster than a WOL monk using that sword that reduces cooldowns by 10 sec. it gives you unlimited dash so you just dash around the screen dropping WOL bombs on melt everything. They definitely have a low ceiling though, so after GR100 and before full augment, you will struggle.

i plan on playing sader for the first time ever in a season. I saw that they have 2-3 builds that are all top tier, more than most other characters. my ideal build would be heavens fury. the starter set sucks though, so it may take me a while to get the gear i want.