Trials HD is actually worth splashing out on the full version, the easy levels are a case of hold down 'A' with your right hand and drink a beer with your left but the medium, hard and extreme levels require more skill, especially if (like me) you enjoy trying to totally complete every level by getting all the speed related medals and stuff.
I've spent soooo much time playing that game it's unreal, which says a lot considering my housemates are all into 'real' games so we have a big stack of games sat next to the xbox.
That is the only contribution I have because I don't play anything else :$
Ohhhh, the other trials game you mentioned is a bit shit really, I downloaded the demo and didn't get into it at all.