Reef ready vs drilling and adding your own overflow? This makes me wonder how ready and prepared you are to do your own drilling, plumbing etc. Are you ready to put a glass drill to a $1,000+ tank? If you are, I wonder why you would even consider a reef ready model.
You need to decide what you can take on and what part of that you are willing to actually do. Go from there.
As far as brands of tanks, do your research and consider manufacturer reliability and longevity (my DSA tank is great!, but the manufacturer closed shop 2 years after I bought it). Also consider what materials you want: regular iron glass, low iron glass, or shell out the money for sapphire glass. Rimless, plastic rims, or polished aluminum rims? Once you make these decisions, your manufacture choices will be very limited based on your criteria. Then just pick one.
Where are you putting this 120 gallon tank? Is it a piece of furniture? If so, now you have to consider stand quality. Do you want a cheap stand in your family room?
And of course, what is your budget. This may limit you to an Aqueon aquarium, or may give you the freedom to get a highly customized aquarium from
https://www.customaquariums.com, pre-drilled with thinner ultra clear tempered glass all around.