In order of gain, it's HBU33, C490, HBU55. The pdf's above are arranged C490, HBU33, and HBU 55, from left to right. Note that without the low-vhf elements, the HBU55 is the same length, but half the width. These data sheets are on Antennacraft's web site in the documents tab for each one.
If it were me, I'd do the 55 if I did anything at all, and was going to go to all the trouble and expense of swapping antennas, but it's not my money you're spending.