I would not wait another whole year for a new iPad. If you’re always waiting on the next one, you’ll never get one. Anything you purchase right now is going to be a crazy improvement over what you have now.
Are you looking for a pro, or just an iPad? If you don’t need a pro, I’d consider an Air 3. You could probably find a good deal on a refurb from Apple, or just a new one on sale somewhere. It’s a nice step up from the base model, with a better display and faster processor, but without the total cost of a pro.
OR, like others have mentioned, maybe get a refurbished 2018 pro.
Either way, I wouldn’t wait. That’s a year you could be using a MUCH improved device.