I was told all new accounts would have the new design editor, no choice any more. Eventually you will not have a choice and all accounts will have to use the new editor. Reason I was given is that some browsers had problems with the old editor.
I have 2 accounts on the old right now and 1 on the new and I definitely prefer the old. I find it much more user friendly and capable of doing more easier than the new one.
Just my opinion. If you never used the old, it would make no difference.