as a daf yomi-er i am tied at the hip to artcroll. that being said, i feel that artcroll has ignored anglo-sefaradic jewry even in its elucidation of shas as can be evidenced by the achronim/late achronim cited (and not cited). the fact that artcroll has never published a sefaradic siddur is curious. the biography issue.
on the other hand, artcroll has published the sefaradic haggadah and rabbi mansours daily halacha so i do not believe it is an intentional anti-sefardic bias, chas veshalom. i think more can be done to encourage artcroll to include our sefaradic brothers and that may also include donations and involvement of the sefaradic community with artcrolls efforts.