Well, let's start for now. I didn't find much information about the multiplier that Goku gives, but apparently it is 1.7x while Naruto's transformation gives you 1.9x, but even so, it is more recommended to get Goku since he is one of the easiest to get.
Naruto is a little more difficult since you have to get 2 scrolls the jinchukiri race 25k gems and Goku only asks for the saijan race and 10k gems honestly it is easier to get the saijan race than the jinchukirin (I don't know if I said the race correctly) but in terms of multiplier Naruto wins.