I have had mostly Williams (EM's) , except for Firepower ,until recently, partly cause I was able to source them cheaper than Gottlieb EM's.
For me buying is mostly about price and the particular game, rather than manufacturer .
I currently have a Bally EM, 2 x Gottlieb EM's , 2 x Williams EM's , a B/W DMD (Creech) and 2 Williams SS but only room to have 4 set up at a time
