I currently run a combination of Yomichan and the Migaku browser extension when looking at unfamiliar Japanese words. I've noticed that one thing that the Migaku browser extension lacks is it it does not list a verb as transitive vs intransitive like yomichan does. This can make it take a little longer than necessary to divine the usage of a word -- and, especially for a beginner -- can make some words (出す vs 出る) look very similar.
I think that would be the most useful but it would be nice if it included whether something was a noun/verb/adjective and what kind of adjective and verb something is for the purpose of conjugations. As it stands, it nearly replaces the need to seek out other dictionaries but just misses a few things.