All 3 series are fantasy series. These series take place in a world that consist of 2 kind of people, people born with super power and people who don't. People who are born with superpower will have ability like super strength and able to do spells. Also, the world in this trilogy consist of many dimensions. For those people who have power they will have alternative counterparts in other dimension (actually anyone can have alternative counterparts because the normal human might have an alternative counterpart with power in another dimension). KO One takes place in the Gold Dimension. This is where Da Dong (Jiro Wang), Ya Se (Calvin Chen) and Xiao Yu (Arron Yan) came from. The X-Family takes place in the Iron Dimension, where the story revolved around the alternate counterpart of Da Dong call Xia Tian. Xiu (Chen De Xiu) is actually from the Iron Dimension but he often travels between Gold and Iron Dimension. K.O.3anguo takes place in the Silver Dimension.
People travels through dimension using the Time-Space Door. Only people with over 8000 points power can travel through. These power points are called different names in different dimension. In Gold Dimension it's called 'Fighting Points', in Iron Dimension it's called 'Special Power Points', in Silver Dimension it's called 'Martial Points'.
In Silver Dimension, people have names and characteristics of characters in Romance of the 3 Kingdom. That's why it's called 'Zhong Ji 3 Guo' in chinese.
Ko One's story is more small scale and not as well developed as The X-Family where they have a complete setting on how the world works. KO One focus on activities in a school and only the last 3rd moving to saving the world. The X-Family is bigger scale and more fantasy than KO One. The X-Family focus on the Xia Lan Xing De family but have a lot more supernatural happenings and have many substories involved. There's also demons, astral world etc.
I think K.O.3anguo again focus in the school, but there will be plot of world domination according to synopsis. I've only started watching episode 1 yesterday. Initially, I just wanted to watch Calvin's guest star role and didn't plan to continue. But now, I'm kind of interested to see how Xiu deals with his 'ordeal' in Silver Dimension. He was forced to take the real Liu Bei's place by Da Dong, Ya Se, Xiao Yu. They outvoted him. So, he's actually very unwilling.
All 3 series has a weird kind of comic style. The comic style is kinda silly but funny nonetheless.
Btw, George Hu is also in The X-Family. He doesn't appear very often though. Only more in the later part of the series. You can check out his character here.
http://en.wikipedia.org/wiki/List_of...88.E7.8E.8B.29
All 3 series has very detailed info in wikipedia. Here are the links. You can check them out.
http://en.wikipedia.org/wiki/KO_One
http://en.wikipedia.org/wiki/The_X-Family
http://en.wikipedia.org/wiki/K.O.3an_Guo