The gx-24 is a Roland, so you are already looking at that brand.

If you want the gx-24, you are in good company around here. Alot of people like that machine for it's smooth operation.
If you want to save a little money, you could look at the "Graphtec CE-5000-40" also called the "Craft Robo Pro". That seems to be the next lower tier down in price that is also highly favored on the forum. Below that comes the Pcut "LaserPoint", but, you do get what you pay for. Not that the Pcut is bad, it gets the job done according to it's owners on the forum.
I'd suggest looking up these names in quotes for feedback on the forum. The extra large cutters are good if you have a need for them. If it was me, if I didn't really have a real need for that extra size, I'd sink my money into a new machine, and the best I could safely afford, and work my way up... just like you were talking about.
Look up a thread called "copam time to compare" and you will find some information comparing cutters. I believe the thread was not finished, but there is some feedback during some testing in there. Good luck to you.