Translation:It is more interesting to read than to write.
Had a doubt to clarify please.
Is there any rule in Swedish to convert an adjective (for example Interesting) to next higher level (for example more interesting) by adding a suffix or prefix to basic adjective.
Further for more interesting can we say mer intressant or intressantare interchangeably.
Thanks in advance.
The basic rule is xare for "more x" and xast for "xest". But like you've noted, you can also use mer x and mest x. I don't know of any rule to find out when you use which, I'm afraid. It's never flat out wrong to use the mer/mest forms - but it can sound very unidiomatic when there's a "proper" equivalent.