I've seen alot of people giving these, but most are highly biased, well I will not be. I have been using X9 for a long time, and I am about to cross over to X10. There are pros and cons for both:
X9:
Pros:
More graphics
Larger community
More resources and scripts
Shop
Cons:
Weak graphics
Awful segments and shading
Not easily scriptable (more heavy scripts)
Community graphics are slowly being killed by the shop
X10:
Pros:
Excellent Graphics
Great modification ingame (deeper characters)
Ragdoll physics
Will soon have shop and graphics packs
Water
Shaders and Effects
Most X9 graphics work with it anyway
Cons:
Less graphics
Smaller community
Graphics pack slow updates
Requires deeper thought (could be a Pro as well though)
Vista Requirement
So in total I would say X10 is better. Please don't flame me for saying this, think of it this way,
X10 was made to be better!
So both have pros and cons, sadly X9 is weaker, and X10 will sooner or later have the extras X9 has, but thats what it was made for! X10 was made as a better version!
My site: www.skyknight.co.uk