heyhey
normally magicka classes dont use 2h weapons in pve content. it actually provides a huge base spelldamage, but light and heavy attacks from your 2h will be weak, when you invest into magicka. since 2h is a stamina weapon, a stamina templar would surely have better damage, but most skills from the 2h skillline are inferio damage wise to those from dual wield. thats why atm dual wield/bow setups are the meta in pve for damage. if you dont care about minmaxing and dont play competitive stuff (vet trails as example), you surely can stay on your 2h wielding magicka templar. it will not be bad at all, actually the damage from your magicka skills will be high, only the light and heavy attacks will be low. for some damage increase, you can backbar a destruction staff for wall of elements, then change for your class skills to the 2h bar and finish off whats left (if the enemy still is alive after elemental blockade disappears, just go back to the destro bar and cast it once more and proceed with the 2h skillbar.
also stamina would be a possibility as long as you arent minmaxing, the race doesnt matter much. so also an altmer can dish out a good amount of damage. just as already mention, dual wield provides the better damage skills than 2h weapons. if you still want to stay with your 2h and go stamina, i recommend to cast the brawler skill once (a cleave ability), then proceed with the stamina morph of crescent sweeps and as soon enemies getting below 50% you can start executing them with reverse slice. again if enemies have still a lot of health, you need to recast brawler from time to time, since it adds a bleed dot.

play as you like, everything is viable till to the point, where you have to decide to play competitive. then you need to think about minmaxing and going meta, but till that point even an altmer can go 2h and stamina, it doesnt matter that much.