the 2 you can pick from is from 2 different regions, Europe and USA, so they cant really be compared. for example people who live in USA would say softlayer is best because they have better speed to there home pc's and the same for Europe servers and people who live there, another example Europe servers have better speeds for files hosts in Europe, but is the same for USA, but softlayer isnt that cheap, i like there resellers 100tb.com but leaseweb also offers good 100tb servers, it all depends on what your needs are and where you need to get the best speeds from.
I like their speeds.