re: Husquvarna 435e/440e chainsaws

Both would be adequate for smaller trees and general use.
They both seem to be the same power head. The 440 with the 18" bar I would expect to see it struggle some in larger hard woods if you really bury the bar deep.
Being a husky it will be reliable and durable. Just remember it is a "home owner" grade saw; they use a clam shell design for cutting cost.

I wouldn't say I am partial to Stihl; I have just always bought them due to local dealer support.
If you wanted a Stihl to compare, I'd look at the MS250 W/ 18" bar. I actually own one. It has slightly more displacement than what you are looking at and it still likes to lug some when burying the bar in hard wood. I wouldn't say one is better than the other, just throwing that out there as they are roughly the same price/weight/length.

I am actually planning to pick up a new Pro MS362 this week for land up keep and handling the larger jobs.