The growth of rest of the altcoins always have dependence over the growth of ethereum. When it comes to ethereum it depends over the growth of bitcoin. Though it has got its own platform the dependence over bitcoin still exists.
Also this one I will not agree, if you remember, XRP were able to take the number 2 spot and it stayed their for awhile, so it really beat ETH that time period. Maybe its safe to say that altcoins can influence the big number of ETH tokens but not the entire altcoins market.
XRP may have been in the second position for some time but that did not last, the only ones that have been able to take advantage of the movements of XRP are short term traders for everyone else it has been impossible to obtain long term profits with it because XRP is unable to outperform bitcoin for long enough, but if you compare ETH and its performance against bitcoin you will see many periods in which ethereum gave great profits so between the two the choice should be easy you should pick ethereum.