The LigerBots use Creo - PTC is a founding sponsor for our team. I have more experience with Creo but have used both Creo and Solidworks professionally, and find the current iterations pretty similar. I find Creo's constraints easier to work with concede that the Solidworks parts modeling can be a bit less frustrating. As an engineer I appreciate the fact that Creo (and other industry standard programs) are exacting about dimensions and positioning of parts - it is frustrating during brainstorming but crucially important for engineering, which is a valuable real world skill we teach to our students. I would say that all of the UI's have evolved over the past decade and if your experience is older than a couple of years, it might no longer be relevant.
Onshape does have a phenomenal ebook on 3D modeling that everyone should read, regardless of the software you actually use. https://www.onshape.com/resources/eb...ng-3d-modeling
I have used Onshape and there are things I like and things I don't like about it (I find it too easy to accidentally change things I thought were locked down). Students tend to love it. I would however recommend testing whether your workspace's internet access is sufficiently robust if you think of going that route.