"Back in the day" nearly every twink had 100HP to chest because the game was all about survivability (Think about Dodge rogues) they were not primarily stacked for pure attack power until late BC and mainly WOTLK. Think about leg armors... 40 stam 12 agility was bis over 50 ap and 12 crit.
Today the game is based on burst meaning the strength and agility gained from 4 stats to chest for a rogue is far superior than 60 hp which is equivalent to perhaps one tick of a dot. Burst is so high that Fiery and Lifestealing are nearly completely unviable due to a mere - 40 HP to your target or - 30 hp to your target and + 30 hp to you which does not make much of a difference when 1500 hp twinks are bursted down in less than 2 seconds.
However with most casters, most do not gain such a benefit as rogues do from +4 stats and in some cases it would be better for a caster or healer to go +100HP.
For a class based on burst such as a hunter, arcane mage, or rogue I would say get +4 stats. For a class such as a priest, resto druid, warlock I would suggest +100HP since those classes are not pure burst machines.
It heavily depends on your class, spec, gear set up and your personal preference
I hope you could gather a few things from this post rather than a typical "whatever your preference is" answer which is the most accurate answer for anything related to twinking.
Best of luck and always consider the possibility of having multiple pieces with different enchants!
~~Mocha~~