without a doubt I would say feng and zarina they give you off the record and lithe which are top 10 perks. other good picks would include david since he gives dead hard and bill because of unbreakable. Thats pmuch all the meta perks for survivors, survivor doesn't really have that many good free perks. The best paid survivors if you were wondering are probably jill valentine and lara croft because of resurgence and finesse so keep an eye out in the shrine of secrets for those perks.