What Type of Older Macbook Would Be Worth Buying in 2018?

What type of older MacBook would be worth buying in 2018? My needs: office, browsing, music, and PDF reading. Is 4GB RAM enough for light use, for the next 5 years or so?

Sadly the biggest problem (in my opinion) with the latest generations of MacBooks is the lack of a user upgrade path, my 2009 MBP has been tweaked beyond recognition including maxing out on less expensive aftermarket RAM from Kingston Memory. I have just upgraded to a 2018 model and had exactly that dilemma along with how much SSD space to buy as that also is soldered on. I have always taken the approach that you should buy the most comprehensive system you can afford, ideally one that exceeds the base spec for your current OS by a respectable margin. In PC terms this means that you won’t have to upgrade for the next few iterations of Windows and your graphics engine will not be overtaxed by the latest games. You don’t generally buy a MacBook with the intention of running high speed graphics intensive applications and even a base level machine should be capable of keeping up with the next five or more years of Mac OS upgrades. I tend to use mine for office type applications, writing and researching, email, browsing, photo editing/art packages and basic video editing. I decided that I did not need the larger 15” screen with separate graphics processor and that the smaller 13” model would suit my needs but with 16GB of RAM - if need be we now have the option to attach an external graphics card so the lack of one is not a deal breaker. Despite all this, as time goes on you tend to find bottlenecks in performance and the easiest least expensive way around them is to boost your RAM which of course you will not be able to do with a current MacBook and so I would say if at all possible, go for the higher spec now and save yourself the possibility of frustration in the future. Remember, as Bill Gates was reputed to have said, 640k, that should be enough for anybody!