The only people who could want to know this are non-pilots who have zero grasp of what it means to have a common type-rating. I have flown all 3 variants (A319, A320 & A321) and would comfortably switch between all of them day to day. Other than the tail strike consideration on the A321 the real differences lie in the different engine types, hydraulic configurations, FMGCs etc. That really is not variant-related but more associated with date of purchase and lease company. Therefore, whoever puts stock on these things are showing themselves up for their woeful ignorance, and by definition are probably best avoided.