With a laptop, I can probably still use a MacBook Pro from 2008. I think the 2008/early 2009 MBP were the greatest MacBook models ever because it had a disc drive and had this critical feature...
Oldie but still a goodie after nearly NINE years...
For a smartphone, nothing older from 2013 when 720p/1080p and quad core CPU on Android became standard. I would love updated versions using the same shells of the HTC One M7, Moto X, Moto G, and Nexus 5. I think the Note 4 was the last great Note phone until Samsung decided to remove features in 2015 including user-replaceable batteries. Both iOS and Android matured by 2013 with iOS7 and KitKat and got better again in 2014.
Tried using an iPhone 3Gs briefly in 2015 and it is like torture. Some devices might age well like those 2008 MacBook Pros but most of them don't. Most smartphones in the pre-2010's decade with their single core CPU, awful resolutions which is half the Retina ppi, 3G speed, and much slower Wi-Fi "g" before "n" really made browsing fast.
The best small iPhone ever is still the SE followed by the 5s. And even going back to a 4" screen is kinda pushing it for me as my ideal minimum is about 4.5" and nothing taller than 130mm in height. I basically would like the same dimensions of the 2013 Moto X and G. The best year for smartphones for me was 2014. We had the Note 4, Nexus 6, OnePlus One, iPhone 6 Plus, HTC One M8, and LG G3.
We started to decline by 2015 with controversial omissions. First with Samsung in 2015 shooting for cosmetic gimmicks and removing useful features like removable battery and IR blaster and last year with Apple shooting for "donglegate" with the iPhone 7 and MacBook Pros.