The best choice would be to have the larger tank and then buy the fish you want.
As a side note, I had a tank that was 8x3x3 and I wouldn't have considered that selection of tangs in it.
Since you posted in "New to the Hobby", it is my assumption that you would value input from those who have been in the hobby for a longer period of time. Experience is our best teacher, and it is nice to profit from the tuition paid by others.