I recently switched from the 2x to the SGS2. Both phones are great hardware wise, but the crap software base that LG delivers make the SGS2 a clear winner. In addition, the screen is bigger, it's lighter and thinner (although probably also less sturdy should you drop it).
The LG is a good piece of hardware though. Once it gets a proper Cyanogen port or Paul fixes the remaing bugs (the latest modaco ROM is much better than stock, but still has a fair share of bugs) it'll be a great phone, but until then, SGS2 beats it by far.