I've used both. As a teacher, Moodle is more flexible for creating course content. It also has some great teacher features like grade me that shows a list of what assignments still need grading. You can see when a student was last logged in and what they have looked at (and how many times). I have posted an example from a student.
You can easily set due dates with cut offs (can't submit late without permission) for each assignment and give extensions to individual students.
They both have rubric systems for easier grading. They both allow you to create sections for organization. Moodle allows you to create user groups so that only certain students can see certain sections. This works well if you have say a 10/20/30 level split class and want to use 1 Moodle page.
For creating content, Google classroom is pretty limited
Whereas Moodle has a multitude of things you can create.
I use the forum a lot where students can post photos and comment on each others photos for an interactive class experience.
Google works for a very basic online class. You can create assignments and Material. It certainly doesn't have the same features as Moodle for a virtual classroom and it doesn't have the same teacher tools that make online teaching easier.
If you are going to be teaching online, I would check out
Which lets you create content that you can use with Google Classroom and Moodle
Which lets you create interactive polls and presentations to enhance your teaching.
I hope this helps