type of experience required for masters I graduated from university last year with a bachelors degree in Mechatronics Engineering. Good learning and GPA is quite good. I have planned to do a Masters degree from the US next fall with a focus on data science (I am very much interested in learning all of computer vision, data visualization, machine learning and using these to solve practical problems eventually - I have made some projects related to these in my undergraduate as well). Unfortunately, where I live in the third world, there are barely any work opportunities in this field and most which exist require years of experience and/or a PhD.

I have been working in a Fortune 500 company as a service engineer for the past 4 months. It's a bit stressful and the job feels quite menial because while there is quite a bit of work to handle, it's simple (replacing parts if a machine breaks down, sending emails, etc) and in terms of actual learning there isn't much. My manager told me this as well. I only get time to research and work on my personal projects after work. But because I have to travel and work overtime quite often, I tend to "miss" a few days which ruins my flow of learning. Case in point is when I was about 25% of the way through a machine learning book but then later hadn't touched in the past 2 weeks because of excess work. So I have to start all over again.

So recently I was thinking to quit and work an easier job I've been offered (which again is not too related to the field I want to get into, but nevertheless a job is a job) that gives me more free time. I even considered the option of not working at all and taking several MOOCs (I feel like there is a lot of good material there), learning as much as possible related to the field of study I want to pursue for the year I am still here. For the record, money is not an issue for me, although not working an actual job at all feels very degenerate and does look bad on the CV.

So my question is: what do the universities really want to see and what would help my chances of getting admission? Corporate experience? Should I sacrifice my "good" Fortune 500 job for an easier one to work more on my personal projects / research? Will this help more because I can mention more things related to my field of study in my SOP? For example I want to further improve some of the things I've made in undergrad but it's hard to find the time to do that with the job I'm currently doing.

Advice would greatly be appreciated. Please let me know if I have been vague anywhere as well.
My suggestion is that you continue your job as Master's programs in engineering departments in the US (at least for many schools) value the experience in the industry before taking on a Master's degree. As for personal projects, it is always useful to be able to present a few in your application materials; however, don't feel like you have to learn everything about computer vision, machine learning etc. before you apply for the schools. It is what the degree is for. 

Having done some amount of work is surely useful, as it shows your genuine interest in the field and being able to effectively articulate why you want to study a certain field in your application statement also carries some considerable weight when it comes to admissions. You can try to focus on a single, but a considerably impressive project on a related topic and present it in your application, rather than trying to take all the MOOCs out there (although Andrew Ng's courses are quite useful).