Only get 7th gen if you're getting 7300/7700hq. 7200/7500u aren't amazing, they get the job done they're small and use little power which is why they're seen in so many slim form factor laptops.
Buy the 7th generation with higher clock speed. the 8th gen only make very little improvement with LOWER speed. also the 8th generation only have screen res of 1366x768 thats too small for an i7 Processor.
Only get 7th gen if you're getting 7300/7700hq. 7200/7500u aren't amazing, they get the job done they're small and use little power which is why they're seen in so many slim form factor laptops.