Neo Geo hardware is much easier to get in Mexico, plus the culture is different in Mexico, remember people play KOF in Mexico like people here play SF, so they have had access to the multi KOF boards and arcades since the beginning and they still draw money in the arcades. Now sure you have KOF Plus which is a hacked version and stuff like that, but KOF still draws arcades money in Mexico so it is still there and it's pretty cheap especially now and days to gain access to those boards. 2002 is more popular than 98 in Mexico because it is a faster game. Mexican style is more about speed than anything else, take a look at Angel and Angel alone personifies what Mexican KOF is about. Speed, overwhelming you with too many options, patience at the right time etc!
How is KOFXI more popular than 98UM? Access. KOFXI came out in like 2005 and 98UM recently so KOFXI has had a 3 year jump on 98UM. In South Mexico SNKp screwed up and they only have the betas for the games RECENTLY..so but they are picking up on 98UM more than ever, and even then, because of how strong they are in regular 98, it does not take them long at all to get to a respectable level in 98UM.
KOFXI SNKp got it right, one version that everyone down South and a lot in the North got access to.
But otherwise simply due to access, regular 98 is more popular, but as I say time is changing, more and more are playing and gaining access to the newer games, which as I say means in due time 13 will be very hot down South...
Also as much as I do know about Mexico, there is a lot still I am discovering, like Kula has played NGBC (when he was using Big against me in 98UM I explained that was where my experience vs. Big came from, how I knew to poke him out with Eiji etc because in 98UM he's just a watered down version of NGBC Big, and he says he knows how to play him in that, we didn't get time for that but OBVIOUSLY something for next time.), SvC Chaos, and there are pockets and areas down South where you can level up in Samurai Showdown, so while KOF dominates Mexico, you can level up in almost any SNK game if you are in the right location. All of this I will be exploring as my quest for domination continues!!! (What better way than to train with Kula, Osmani, Luis Cha, Kane999, Zeus, and top Mexican players???)