My biggest issue with EFF is that they often take pro-corporate positions and is lead by many actual executives and former executives (see board of directors https://www.eff.org/about/board), while the ACM comes more from an academic or tech worker strain (see https://www.acm.org/about-acm/officer-bios).

So while I agree with the EFF on many policies, their corporate leanings are a turn-off and isn't, imo, a solid ground for people doing day to day work in computing.