The Origins version is easier, but if you beat it you can unlock the original difficulty. As far as the "added features"...

Dash does not make the game any easier, but it makes catching the chocobo laughably easy. Not that this was ever terribly hard in the first place.

The select cancel trick was in the original, so it's kinda moot.

Auto-targetting also doesn't make the game much easier, but it does make battles a little more mindless. This can be good or bad depending on how you look at it.

FFI's features in Origins did a lot to make the game easier (reviving/de-stoning in battle is the most obvious), but FFII's didn't cause a huge drop in difficulty.