Can't go wrong with the obvious choices in either the Fire or Ice Epics, with Fire probably the more favoured. Powers of note are the single target hold and ranged attack(s) included.
Energy Mastery, although kind of out of place in your kind of powerset choice, is also heavily favoured due to the greatness of Conserve Power and Focused Accuracy. MBar's got Energy Mastery and only those two powers from it, and I can certainly recommend it. 
conserve power-large downtime, gimped. Energy mastery was the power ive always had, until now.
Fire 'tanks' ( i use the word very loosely ) these days are nothing more than pseudo-scrappers. The only way to survive is to kill them as fast as you can. I have now gone from being a tank ( pre ed ), with these powers;
Conserve Power;Presence pool ( extra taunt and fear );Hasten, little overall damage capability
to
ROTP ( self rez, after i swore id never take it ),Boxing,Tough,Assault,Tactics and most importantly epic wise: Block of ice;Ice blast;Ice storm
I know crazy huh? No. I now have a large aoe slow, a good single target hold, a nice bit of ranged damage/slow, and with all the end/red and recharge in almost all my powers im not missing hasten/conserve power much.
The beauty is the AOE slow. Gives you the few extra seconds to 'knock em down before they do you', and the single target hold/slow stops those bosses hurting you so fast.
In trials it seems ok so far.
which is the best epic power pool set for a fire/ice tank to get. Any1 got any sugesstions please? Cheers.