Which job should I take?

I have 2 job possibilities for this summer.

The first job (which had last summer as well), is a job with pools. I open, close, maintain, and build pools for a company. I get tons of hours, good pay, and it's a job that I VERY much enjoy. I work with a friend unsupervised, so there's never anyone looking over our work. By far the best summer job I've ever had.

For that reason, I didn't even apply to anything else. However, today a professor emailed me offering me a job as a research assistant (in physics) for the summer. Normally, those jobs are jobs that you are lucky to get if you apply. Here, it's being OFFERED to me! Moreover, I would ALSO get to work with a friend, as my study buddy works with this professor in the summers.

The issues are:

1, My goal is to be an engineer. I just finished a bachelors in physics (I was undecided at first), and now I will do engineering. The research job is more physics and computer science related. I'm not sure whether it would actually further my career in engineering, though, it's probably better than a pool job.

2, The research job pays half what the other does. I will need the money to pay for engineering school.

3, I already know I love my current job. I don't know about the research one.

4, I am tired of studying. Another reason I didn't even apply to a research position is that I wanted a break from academia for the summer.

I don't know what to do. An opportunity like this doesn't present itself every day, so I'm split.