I really think we should work to find something that will keep both sets ingame and viable. Obviously the offensive vs defensive wont interest people. So we should look to something like accuracy bonus vs strength bonus. (Similar to the arcane necklaces) Another option would be making one set more viable for hybrid styles, while the other set has higher offensive bonuses for its main style at the cost of negative bonuses on the other two styles. This will be much easier to see with the numbers.
Here are the current stats of all 6 boots. The stats are actually really similar. Probably much closer than most people think. They are boots after all and don't have very high stats to begin with.
Here is a concept that makes the Cerb boots BiS for using a single style, but keeps Glacor boots extremely useful and viable for hybrid pking/pvm. While the Cerb boots have higher attack bonuses for their respective style, they have high negative bonuses for the other two styles. The Glacor boots have lower attack bonuses in their respective styles but no negative bonuses in the other two styles.
We don't have to go with something exactly like this. We could even switch this proposal between the two sets.
The point is, we have so many options for balancing these boots and keeping both sets ingame. It makes no sense to remove content. Not every item has to be Best in slot for every stat. Variation is what keeps the game interesting and forces players to make choices. Want a higher attack bonus in melee, well it is going to cost you your mage attack bonus.