Level 0 and Level 4 are the best choices, but in Level 0 there's no supplies, so you'd probably die from dehydration when the week ends. And for Level 4, its clear. you can be with people here, there's supplies, and sometimes there are entities, but you can fight them off. Idk bout lvl 21 though. (assuming its not very good because 4/4 people here (so far, have voted for lvl 4.))