First things first: decide what it is you wish to teach your students.
- fundamental exposure to robot technology
- simple programming via Teach Pendant Programming TPP
- more complex programming with structured language
- simple pick & place or more complex path applications
- systems integration (sensors, grippers, vision systems...)
I'd say all of that starting from the easiest approach (teach pendant) up to structured language programming. If we go for an ABB Yumi arm we'll take advantage of its gripper which comes with vacuum and vision (as options) as well.
Our students can program in C and python and have an electronic background while lacking on pneumatics and mechanics.
I consider RoboDK an easy way to approach industrial robots while being less useful if we go for an ABB solution with its own simulating environment (RobotStudio).
We didn't consider minor cobot vendors because we will need a well established solution with good support, both as documentation and people to reach when issues arise. Then there's the market presence in our area to consider when choosing a particular brand. Industrial robots are more and more present while cobots are not so choosing a platform that suits both should be better.