This question gets asked so much and the truth is that none of it matters in the slightest. Everquest gear choices are completely ineffectual in the modern game (max level/current xpac). Even if you don't specifically stack hDex, you're going to get a lot of hDex just from the gear available at max level. So as long as you're upgrading to the highest tier of gear available to you and getting the newest augs from every expansion, you'll be fine.
That said, general theory crafting says for melee characters to go for hDex until your crit rate is 100%. Currently, only Berserkers and Warriors will actually achieve 100% crit rate as they have a naturally higher base crit than all other melee classes. Rogues and Monks are still probably a few expansions away from being able to cap crit rate at 100%, at which point there will probably be another significant stagnation among melee players. As a zerk player in a raid guild, I choose to aim for 4000 hDex with full buffs, trophy, tribute, power source, etc running and then each subsequent upgrade after that should go to the 3 other melee centric stats (hSta, hStr, hAgi). I won't keep an old aug from 2 expansions back just because it has a few more hDex on it when I am giving up more overall stats from all four categories combined by upgrading to an aug from the current expansion.
Overall, though, if you're expecting big DPS gains by moving around a few stat points here and there, you're going to be dissappointed in modern Everquest. Any actual difference from this type of adjustment is going to be so minuscule that you will only notice it when analyzing 100+ hour long parses.