ABET accreditation for CS is not strictly needed. The presence of such indicates that the CS major meets a good minimum standard (but also requires significant non-CS science), but many non-ABET-accredited CS majors are good (e.g. three of the big four in CS offer non-ABET-accredited CS majors). However, some of the non-ABET-accredited CS departments have rather limited course offerings, so it would be wise to check catalogs and schedules. There may be some “CS” majors at some schools that are more like business based IT majors rather than more technical CS majors, so that is another thing to check if not ABET accredited.