People recommended his fights against Eduardo Marquez, Daniel Reyes, and Bustos a while back (they've been on my to-watch list for a while now).
Varela and Cazares come to mind as well. Segura 1 was a great fight although Ivan lost by KO as he was already in his mid 30s, ancient for a flyweight.
Lovely boxer, wonderful mover, I loved him. Went off the cliff like an absolute mother****er, you could kind of see it coming but it still stung. Even guys who at the ring up tended to get nowhere near.