I disagree with the generality that if you have 4WD, you will always push too far and get stuck. Some people do, some don't. That isn't the fault of the tractor, but the operator.
We live in the mountains, and 4WD is invaluable. Better braking, easier on the land, greater accessibility, more sure footed, better using the loader, safer to mow with, and on and on- I don't think there is a right or wrong when it comes to 2WD vs. 4WD, and these posts that keep seesawing back and forth about which one is right gets SO OLD. If you need it based on your conditions, get it. If you don't, don't. You can make whatever you have work. Perhaps it isn't in your budget- so don't get it, and learn to use what you have effectively. Perhaps you want to ensure a better resale price- 4WD will do that. I wouldn't consider a 2WD tractor, unless the price was rediculously low. And then, I would sell it for a profit and buy a 4WD.
My answer- buy what you need and can afford, and then learn to use it to the maximum of its capabilities. A 4WD is no good if you don't know how to wisely apply it, and a 2WD can get an amazing amount of work done, if you know the tricks.