They are both, basically, good choices. The graphics on the ASUS is GT520MX, so is only "entry" level, which will not give a huge boost, over the dedicated graphics on the i5-2430M. Having said that, it will give some additional capability for things like photo/video editing, and will play some games, if you are interested.
There is a greater arguement in favour of 8GB RAM. You can almost never have too much. Having said that, 8GB RAM in the ASUS is only £20 more.
Both will "claim" good reliability, but, statistically, there's not a lot of difference. It's a bit "luck of the draw" with any make.
I'm not suggesting that you should buy from them, but if you have a local Computer World, or Comet, go and try them out. You could find one "feels" better than the other.
One thing which is not detailed on the SOL site is webcam resolution. You could check on the manufacturers' website that one is not better than the other.