All chainsaws require tension and oil on their bars to operate correctly. For this reason, the tensioning and lubrication systems that your chainsaw is equipped with will considerably impact your user experience.
As you can tell from our list above, most chainsaws today have automatic lubrication systems and simple tensioning knobs that can be adjusted without using tools.
Check the specifications on any unit you're using or looking to buy since some models still include older manual tensioning systems.