We know that modern lexica are important for providing information on how modern scholars understand the meaning of words. And we know that ancient lexica are even more useful for providing information on how ancient scholars understood the meaning of words. So it is interesting to read through Roger Pearse's useful list and discussion:Lexicon: an introduction to the dictionaries of ancient Greek that survive from antiquity.
PS. We also know that such lexica may preserve interesting text-critical information - on one of which see Dirk Jongkind, "Some Observations on the Relevance of the 'Early Byzantine Glossary' of Paul for the Textual Criticism of the Corpus Paulinum", Novum Testamentum 53 (2011): 358-75.