My first 2* was Orlando, though i did not use him for long he was kind of a filler card who i replaced with
My first 3* was Katherine, served me well i got it leveled to about 26 but i got a 4* poison level soon after that so it was short lived
My first 4* was Helmut, but the first 4* i actually used was Sergei whom inspired my love of knock-back units, i have maxed him and still keep him to this day.
My First 5* was Zhou Yu i pulled him first try from an event box, this was my leader up until recently, i plan on keeping him just because i liked him, he was truly my first leader and i have been through much with this guy
My first 6* i got recently(5 days ago) and have leveled up to 81 at the moment, Eurydike, which i am guessing is a fairly rare unit because people offered me 2 maxed 6* and a maxed 5* for her, but i'm keeping her for she is my first 6* and i'm sentimental like that.