It depends. You should analyze the competition for BOTH keywords and the search volume. You have to decide if is a smarter choice to go for the easiest or the juicie$t (if they are not the same).
one has 23M competitor sites the other over 100M the 23M will be easier to crack. However one may convert better that the other. eing #1 does not automatically make money or generate traffic. If you have access to hitwise you could use that. I am surprised that there are no ads in google for those terms.