I’d strongly recommend matplotlib. It has a matlab like procedural interface that makes it very easy to pickup if you’re coming from matlab.

Additionally, it’s wonderful to be able to “dive under the hood” if you need to create a special type of visualization: i.e. the internal model is easy to understand and highly customizable. This has enabled me to create several awesome plots that would have been very difficult, if not impossible to create with any other plotting program or library.