Join Date: Feb 2017
Location: East TN Sevier County is Near Knoxville
Pretty much comes down to personal preference: Style & Appearance, Comfort for person use (seating, getting in and out, interior arrangement), and Warranty.
I never looked at the IONIQ, just had an interest in the NIRO that developed into a quick buy in FEB of 2017.
Don't like the style of the IONIQ (again that's a personal preference and no reflection on what others may like). Mechanically, suspect one as good as the other but warranty is better on the IONIQ.