What sort of computing device you need depends on a large number of parameters. However, there are some simple rules of thumb you should keep in mind:
As a general rule, avoid new gadgets. Stick to older machines for many reasons. No specific year is mentioned, for your needs may change, but always keep looking for an "as old as possible" device first to do the job.
Also, look for "golden periods" of "golden companies". As a general rule, companies come and go and they follow normal evolutionary cycles (they were born, they reach their zenith, then they decline and die). Look for three kinds of products: their a) first product (it is usually the most innovative one), their b) peak product (probably the most mature, solid one) and finally, their c) last or penultimate product (usually the best value).
Always look for the oldest possible solution for your need, and only move to a newer one if the older one does not fulfill your needs entirely.
Where you acquire your gadget from also matters. Certain groups of people have better grips on things than others. As a general rule, regions in colder climates with pragmatic work ethics, coupled with a fanatic attention to details are good at making products worth getting.
Without mentioning specific countries (check the globe of the planet you live on for reference), focus on groups of people with a long history, a track record of civilization building, culture and sophisticated ethical, moral and judicial systems. These groups of people usually produce things that last a long time, are faithfully and honestly designed, built and sold.
Once you identified your preferred manufacturer, immediately check for their oldest products, keeping in mind the principles mentioned in the opposite column regarding time.
Look for markets trading with such tafinaf items, or if you realize no such market exists in your neighborhood, be one to start one and help others while helping yourself as well.