Which query execution will be faster
In normal circumstances the JOIN is the structure that would be recommended for performance reasons. However, it looks like you're attempting some kind of search functionality.
Btree indexes don't work well with the kind of filtering you're implementing:  

WHERE LOWER(b.comment) LIKE '%home%'


Using a function on the data (LOWER) will render any index in place useless as well as the wildcard filtering %string%. The query will likely run okay on small tables, but will suffer the longer it gets more rows that are scanned. This access type is eased with Fulltext indexing and relative matching rather than table scanning.  

You might also try using a dedicated search product with inverted indexing like Elasticsearch, Solr or Sphinx.