it all depends.
@Joe Glass Cages custom builds tanks, so does Planet Aquarium (Used to be OCEANIC!!) They can build you a custom to the specs of what your RS was I bet. Probably even put drains etc in same places.
I am biased against Red Sea, you should know that. I Authored one of the Red Sea Fail threads after doing a few days research on these forums. I was that amazed by the amount of fail stories I found. So I will NEVER recommend you replace a Red Sea with another Red Sea. They re-issued the G1 series after a re-design, basically admitted they had an issue but the Customer Service nightmares I have read about those issues was all I needed to run the other direction.
The other end of my Bias leans to Planet Aquarium. I have a 30+ year Oceanic tank. I love it. It still holds water. Looks great and takes up one whole wall of my living room. (See my build thread) I would also recommend an All-Glass aquarium if you can find them. I have a Double Drilled (2 bulkheads on each end) 6ft 125g I use for a sump. It's a solid built tank with thick glass.
Which ever way you end up going, I wish you good luck.