On the chainsaws a 50cc Stihl MS260 or a 62cc Stihl MS360 as you will have to buy these used. The newer emission friendly saws that replaced them are more expensive to keep running and harder to keep running right. Another poster mentioned the MS440 which is a 71cc saw and one of the best.
I have had a Husqvarna 545 for almost 3 years now.. It still works great. Have cut probably a dozen cord with it. It's actually a Jonsered but they're the same saw with different paint.
It has the electronic Autotune carb, haven't had a lick of trouble from it, and it's always in tune.
The MS360 is an old saw, and are tough to find used. The MS361 replaced it, and the 362 is the current model. All good saws though.
The Echo CS590 is the best saw for the money in that class. Make sure you get it tuned right, as they are set very lean from the factory.