Was an EM virgin until 3 weeks ago - so I will wade into this one...
If you are electrically competent - and have good troubleshooting / fault finding skills, I think EM's are a lot of fun.
The first time you drill the start button with "the hood up" - is a real "holy shit" moment!
To me - the hard part is knowing WHAT it is meant to be doing. (Being on my first EM - this is where I struggle), I find the actual mechanics / electrics to be very simple and easy to repair.
However, if that is not the case - A modern SS pin is the go, look for a 90's or later Williams/Bally - a LOT easier to fault find, and a much larger knowledge base to help you out.
I am very lucky as several members have an identical machine to me (Pro Football) - so I have that knowledge base to draw on.
"Hey - what color wire goes on terminal X?"