I personally prefer the JP version of Kof Orochi Saga over the US version. To me it was a case of quality vs quantity. The US version of orochi saga may have added two extra games (kof'94 and 98) but they took out alot of game content. The game are very basic emulated ports of the arcade version and some of them had errors (e.g kof'98 on the us orochi saga was pretty badly done).
The japanese version had less games (only three kof games) but they're more "complete" in terms of content.
One major thing that disappointed me was that they omitted kof'94 which was technically also a part of the orochi saga. Sure, hints of the orochi power were only slightly mentioned only in kof'95 and not '94, but nevertheless '94 is a part of the saga even if it mentions or introduces nothing about orochi.
They most likely left out '94 from the Japanese orochi saga because the Japanese developers wanted to profit fom Kof'94 Rebout. It's the same reason why kof'98 wasn't included as well because of kof'98 UM.
I can completely understand leaving kof'98 out. For one: '98 was technically a dream match and not part of the story "saga" and also: kof'98 UM is a superior game and worth being it's own standalone game.
kof'94 Rebout is NOT as good as UM to be it's own game. Not to diss kof'94 rebout but that game was for the most part; the same rehashed game of kof'94 but with new looking graphics over an old game. It wasn't really a "new" game. Instead of just remaking kof'94 when they made rebout. Rebout should have been a game that combined '94 and '95 so that you have the best of both. The UM series had enough changes and improvements over their original versions to be a new game.
I didn't like kof'94 rebout as much and it's not worth getting just to play classic kof'94. So for fans of the Japanese orochi saga, if you liked kof'94 or '98 you have to buy them as separate games. As I said: Kof'98 UM was fine and worth it.. but kof'94 rebout wasn't exactly.