You are asking a question about style rather than grammar.
Your two sentences mean the same thing.
The sentence including “which is” is typical of spoken English. When people speak, words are produced as the mind builds thoughts, typically in sequential fashion. (I have known, however, at least three brilliant people whose thoughts outraced their ability to string words together. They frequently strove for conciseness in speech and ended up sounding like idiots.) Most people thinking carefully do not originally produce succinct or even elegant prose. Moreover, people listening to speech need time to parse it for maximum understanding. The “which is” construction is natural and perfectly acceptable in speech and casual writing.
The modern style in writing prose places a high value on conciseness. The only higher value is clarity. If you want to be considered a modern writer of professional caliber, the adjectival phrase should be used more often than non-restrictive relative clauses. Of course, sprinkling in a few non-restrictive clauses avoids tedium in your prose. But style is partly a matter of subjective feeling and partly a matter of fashion. It is not a matter of right and wrong.