Both Discover University and Strangerville are great packs and I use the CAS, items and World from them frequently. Strangerville has some of the best music in the Sims 4 too imo but overall DU has a lot more gameplay and replay value (Rightfully so as its an Expansion pack and not a gamepack). DU is not good for rotational play though, you basically need to only play your Uni household to get good grades and with the length of each semester it's best to turn aging off or put lifespans on long so you have enough time to do everything and not have everyone be elders by the time you're done.
Anyway I don't know what your budget looks like but you can always do the create a bundle as well and get both with a stuff pack.