ISIS vs OSPF

[abdul.qadir5001]

What is a main feature that makes ISIS better than OSPF?

[balaji.bandi]

This has been  discussed in the community, here is a good link that can give you more information :

https://ipwithease.com/ospf-vs-isis/

depends on the use case, we can not compare OSPF with IS-IS (ISIS working different way) - each one has its own pros and cons, but OSPF is used in most cases, But in SD-ACCESS Underlay Cisco  Prefered to use ISIS as Flat network.

[abdul.qadir5001]

Dear but as per my understanding ISIS directly support IPv6 but In OSPF we have to enable OSPFv3 so this feature of ISIS makes it more prominent than OSPF. You also think like this?

[balaji.bandi]

As i mentioned depends on use, can where you like to use was the use case.

[Joseph W. Doherty]

How do you understand IS-IS to be better than OSPF?

Understand, routing protocols are much likes "tools", some do some jobs better than other tools.