Here’s the list I compiled, trying to decide which combination of consonant plus long-e sound would make a good choice for a non-gender-specific (gender-neutral or epicene) pronoun, in the subjective case:
be — too confusing, given the verb, and the insect
ce — no one will know how to pronounce it (‘key”?, “see”?, “chee”?)
de — maybe; could be confused with Delaware, or Brooklynese for “the”
fe — reminiscent of “fee-fie-foe-fum”; the person would be a contingent “fee”; symbol for Iron; Spanish for faith, trust;
ge — confusing pronunciation (“gee”? or “jee”?); it’s the Greek-based prefix for earth; and the symbol for the chemical element germanium
je — it’s not found in any major European language (which is a plus), but it sounds weird (especially its possessive and objective forms)
ke — lots of homonyms
le — means you/yourself (sing., polite) in Spanish;
me — already taken
ne — confused with Nebraska, northeast, or New England, symbol for neon; variant of nee (born)
pe — very unfortunate slang homonym; means “printer’s error”; Phys. Ed.; Pro. Engineer
qe — who? why? what?
re — too many homonyms, and means “the thing”
se — confuse with “see”; selenium; southeast;
te — Spanish for you (obj. singular, familiar); confuse with “tea”, “tee”
ve — confuse with letter “v”
we — already taken
xe — pronunciation problem (not “ex-ee”, please!); symbol for xenium
ye — archaic for “you”
ze — maybe, but perhaps sounds too French; sounds like letter “z”