I've seen a few posts now from people saying that they are going for the 12.9" because they expect Apple to make changes in iOS 13 that will make the iPad a better "laptop replacement" and presumably at that point they would rather have a larger screen and would be sorry they purchased the smaller 11". This may be true, or it may not. And in any event I assume iOS 13 is a year away?
I'm not suggesting that someone who prefers the larger screen shouldn't get a 12.9". However, my own experience has shown that making decisions based on what I expect Apple or another company to do rarely works out as I anticipate.
I think it makes more sense to buy for today's use and make adjustments as needed down the road based on real facts rather than conjecture. If your work requires a laptop, I suggest it makes more sense to buy a laptop. If an iPad does everything you need and you can perform your work better with a larger screen, then that's what makes sense for you. And if you feel the smaller form factor better suits your usage, the 11 inch is the answer.
But I would be careful buying a 12.9" (or an 11" Pro for that matter) primarily because one thinks that there will be changes to make it more like they want it to be.
Just my 2 cents. YMMV.