Machine learning is a very interesting field. Part of the reason for this is that most of the novel work in the field happens outside of journals. Instead, largely because it advances so quickly, it’s a very conference-driven space. The three biggest conferences are NIPS, ICML, and ICLR. There are definitely a few others, but if you review all the papers submitted to those three conference you’ll have a very good sense of state-of-the-art.
Most of the cutting edge research done in ML gets placed right on arxiv. A lot of the reason is that it’s such a sexy field that ML researchers are largely exempt from the traditional iron grasp of Elsevier.