Chains get dull no matter what you are cutting,But cutting logs that have rolled around in the mud will quickly dull a chain. Also Drier logs will tend to wear the chains faster also,especially Elms and other knotty hardwoods.
I use a old Mac but they are out of business,So If I were to buy a new one it would be a Stihl or a HUSQVARNA .
Depends on how much wood one cuts,A cheaper saw will do the same job but wear out sooner.