If you see files such as .classpath, .project in the project directory, then it is probably created using Eclipse. If it was created using NetBeans, you will find a file called .nbproject.
Regarding the new question that is best suited for the IDE, there are many wars around which the IDE is best suited. I prefer Eclipse, others prefer IntelliJ IDEA, others prefer NetBeans or others. They all know to open a project based on Maven. For example, I use the m2eclipse plugin to import into an Eclipse workspace.
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