Having a near universal language, which is learned as a second language by most, has plenty of advantages. However I think such a language would need to be easy to learn and fairly straight forward.
Chinese, and to a lesser extent Japanese, both have logographic systems that are extremely difficult to learn. I do realize there are methods to get around this but I'm still skeptical.
English is extremely flexible, which makes it easy to expand - a must for any "universal" language. However it is also rife with exceptions, variants, and irregularities and this makes it quite difficult to master.
If you'll forgive a momentary aside, from my understanding every state in India needs to include Hindi or English in their official languages - and many chose English because it is neutral (Hindi empowers its native speakers). It seems to me if we want a universal language we should follow this and find something viewed as relatively neutral. This would likely be a language which isn't too widely spoken to specifically take out the power houses.
Off hand I think a language from a prominently Neutral nation would be good. Switzerland isn't going to work, it's primary languages are French and German. Swedish seems like a good bet. Finnish is even more niche but it's an agglutinative language and while I personally find them very cool I'm not sure how easy they are for others to learn.
If Swedish is riddled with irregularities like English then it may be a poor choice, otherwise I think it could work well.