CorelDRAW-like node behavior: intuitive select/deselect, maintain shape when deleting a node, two-sided handles.
Years ago, the most painful switch from CorelDRAW (10) to Illustrator (5.5, then CC) was the bezier drawing behavior. I have no experience with newer versions of CorelDRAW, but I'm assuming they behave similarly to v10.
1. CorelDRAW required fewer clicks to select, manipulate and deselect nodes and the lines they live on. Also, the switch between the normal and direct selection tools (white and black arrows in AI) could be done without returning to the tools menu.
2. When a node was deleted in CorelDRAW, the software "did the math" and maintained the overall shape (when possible). That's very helpful when you're trying to delete a node in order to smooth something out: you can actually start refining your curve immediately, instead of first having to "fix" the part of the line that collapsed when you deleted that node.
3. All nodes featured double-sided handles for both nodes of a line section, while AI only shows one side. Sure, you can technically make the same modification from either node on that section, but being able to use either side was far more intuitive and ultimately sped up most tasks.