To help you out!

Final Fantasy XI Online is online only. Reason is if there was offline section, no one would play it online. So they had to make it totally online.

Rest of Final Fantasies offline, so don't worry. Only one online Final Fantasy needed due that they last forever with updates and patches. Everquest was out more than 5 years plus and just continues with patches.

I thought FFVIII was a great game. Many people couldn't get use to unique gameplay or hard bosses I guess? Every Final Fantasy since FFVII rules in my opinion. There all had strengths and weaknesses. But every new title brought something to series!