I think the 12" 2017 model with the i5 was the best one. The i7 got a little hot...

stock_toaster on Aug 4, 2020 | parent | context | favorite | on: 27-inch iMac gets a major update

I think the 12" 2017 model with the i5 was the best one. The i7 got a little hot, and the m3 was pretty slow. The i5 (I'm still using it today and it works great) doesn't suffer from heat issues nearly as bad as the i7.