Only reason to NOT use Windows 7 is compatibility with newer software/hardware, so unless you got something too new to work on it or have HoloLens/other Microsoft headset that requires Windows 10 you are fine with a 100% functional and VERY ergonomical OS that can do everything you could want and more, while it also looks very simple, intuitive, sleek and is pretty light with a very good degree of backwards compatibility (even if 16bit mode was disabled, but it's easier to re-enable on Windows 7 than any other OS).
On the other hand, Windows 10 is a buggy broken mess, with occassional "updates" that if anything break compatibility with software/hardware if not introducing additional bugs on top, all while being full of bloatware just because Microsoft seems to care more about knowing everything you do rather than having a properly functioning OS and it's not even that simple or ergonomical either, looking like a Frankenstein's monster of an OS, having both Aero and Metro, with UIs that are a clusterfuck and if you want to find even the simplest of things, only fast way to do it is to use the search function for EVERYTHING, especially with how enormous the start menu gets after installing bunch of things and whatnot! Sure, you can tweak the UIs very slightly, but it's still bad, while on Windows 7 even the default layouts are very nice.
PS: On the note of Vista you mentioned in the OP, the reason Vista got hate was only for the Vista Service Pack 1, because it was possibly one of the worst OSs ever made for a couple reasons. It introduced THOUSANDS of exploitable bugs hackers could abuse with hardly any work, broke compatibility for MOST important programs, even Microsoft's own Office Suit, causing it to either not work or repeatedly asked you to purchase extra licenses even if you had just bought one, was the OS that stopped compatibility for 16bit software meaning literally NO backwards compatibility under any circumstance as "XP Mode" wasn't a thing until Service Pack 2 and so so SO many other problems! Then Service Pack 2 was shat out with plenty issues on it's own, but at least it fixed a bucketload of SP1's problems. However, the whole "Vista" thing was bad PR so Microsoft pushed Windows 7 ahead of schedule to save their stocks and hopefully make people forget about it (nobody did
).