Replacing LM324N with Better Opamp

[m718]

Can PNP input opamps be replaced with NPN input ones?
I want to replace the LM324N with something better.

 

[berkeman]

Can PNP input opamps be replaced with NPN input ones?
I want to replace the LM324N with something better.

A FET rail-to-rail opamp would be able to replace the 324. The PNP topology was just used for some applications before good FET opamps were viable.