My main is a nature pure healer with 48 skill points i can solo most stuff with it and it's the only power i've leveled past 10 lol. I just can't get into the other powers because i'm so used to my healing nature powers and i don't think i'll be able to survive later missions with other powers solo.
Take old gotham subway in duos for example, this guy stops playing at the final 2 bosses in the last room and i had to solo it. I beat bane and penguin without dying in healer role, i don't think i could have done this solo with any other powers.
But my original question was what is the best solo power for each role? Everyone here said ice for tank okay, so what about dps and controller?
I solo pretty well with my gadget controller. Taser pull to start fights to avoid getting mobbed, anesthetic heals with only 1/3 supercharge, gause grenade and cryofoam provide decent crowd control and a power interaction Keep PoT up and you can use your powers pretty liberally
Your entire post can be summarized as-"Rawr, I'm an angry troll"
You could make a strong case for Nature. It's probably the most versatile and well balanced powerset in the game. With the right loadout, you could basically run as a DPS, Tank, and Healer all at once, and Nature excels when it comes to stacking Damage Over Time as well as having a very strong 'bosskiller' weapon in Impaling Thorns. It also has a very good return on investment for your power use (unlike Electricity, which hits like a truck, but sucks you dry...). For example: