Everyone will prefer bitcoin if we need to choose.Having a high price is very important. Fraction of investment on bitcoin will.give you enough fortune and bitcoin already become the foundation.
I really do not know why people even ask which to invest anyway. The main rule of investment in any form is to diversify so as to at least spread all the risk and no one will even want to put all their eggs in just a single basket anyway. I am holding both of these even though I am holding mostly in bitcoin, and I have always traded my alts at their peaks since most of the time, they always get so beaten than you can imagine once there is a pull effect from bitcoin.
Diversifying even suggest not to go for big percentage into one single opportunity, I am preferring to go with bitcoin with major shares as I am very much confident about the returns of bitcoins compared to ethereum or any other crypto.
Both bitcoin and ETH are very good options for the sake of investing your money and that both coins can help you in making of large amount of money as well. It is you who need to make the choice in between these coins and that too by looking at the market condition and above all, choosing the right coin and that too based on your own planning and the duration for which you are planning to invest your money.