Nothing but Photoshop can read and write .psd files 100% correctly. There are even differences among Ps versions. The .psd format is tied to Photoshop internals very tightly. Some limited import is possible but that is all; editing .psd files in anything else than Ps will most likely result in loss of some parts of…

Paint.COM is a too new score good in this test. Too bad.

"best" is a dangerous word when applied on masses... It only works well on single person, single purpose and single moment in time.