Should I buy iPhone online or offline?

[fakemishra]

I am looking to replace my old android with iphone. Budget minimum but should get me by for 3-4 years atleast
Two questions:
1) Should I buy online or offline?
2) 15 series or the base 16? Not even considering the 'e' version

 

[Heisen]

The feeling of touching and experiencing is something else’s