the stuff you 2 are saying might be right, but it's something someonne at 92 can't use at all
basically, i wouldn't max more than 2 51 skills, and only 1 in the beginning. that means: max out the 51 light one because you'll use it the most in pvp because it will get a huge damage boost by imitid lightning
then the 81s: The only one maxing imo is the Thunder Spear, but hear it comes to ur own decision. I would rather max out Energy Hammer because Thunder Spear misses in pvp sometimes and hits max 5 targets. The damage is cool and in PvE the combo of Imitid -> Lightning Circle -> Thunder Spear really hurts, but I don't know to be honest. I'm 150 and got Energy Hammer at 3 and heading to have it maxed.
Max the one of those 2 which you enjoyed the most. at 157 you'll have both maxed out anyway ^.^ Be careful when you max out Energy Hammer. You'll have less points for ur 92s because it energy hammer has lower lvl reqs than thunder spear -> ealier maxed out -> earlier SP used
Get all your masteries and all buffs to Max
Also Max out Spoiled Divinity, Urzer Gain (and Aqua later at 98+) and get ALL rest skills from ur Energy-Tree
Get all Skills from Fire, Ice, Light, too.
Max out all 3 92's
So what to max out:
Mastiers
Buffs
Aqua Circle
lvl 92 skills
lvl 51 lightning skill
Thunder Spear or Energy Hammer (Thunder Spear is in my opinion more mainstream, Energy Hammer more alternative

Energy Hammer requires a good wand more than Thunder Spear, too, because it hass more hits and less skilldamage)
Later at 140+ you can max out Thunder Spear/Energy Hammer (depending on what you chose to max out first) or the 51 Fire Skill (less people use Fire resis than Ice and it deals more damage than the 51 ice skill)
Hope that helped

Else go to the official 2moons forums and check acidd's guide (should be on page 2 in the mage section).