ESDLIFE website's coach seems not pro (without lisence): 1 coach vs more than 10 students sometimes (I saw) on 1 court.
LCSD coaches are usually Level I, some are Level II: 1 vs 18 on 3 courts.
YMCA will have courses: 1 vs 6 or 8 on 1 courts
HKTA website's has course: 1 vs 6 or 8 on 1 courts and you can goto coaches database to check all the registrated coaches (private) data (Level 1, 2 and 3).
Course lessons will be cheaper, but lining-up alot. Private coaching will be more expensive.
If you haven't ever play: Suggest taking course first to see whether you like, then private coaching.