Since the class system in Elder Scrolls Online is pretty different from your average MMO, determining the best solo class is almost impossible. Each of the classes in ESO can fill all roles whether it be tanking, dpsing or healing. They all bring something unique to the table as well.
In Elder Scrolls Online it does not come down to what class is the best at soloing, it comes down to how good you are at soloing. How you build your character is also important. Someone who groups or raids a lot will primarily want to build for one of the archetypes (tank, healer, DPS). With someone who wants to solo, you will want survivability and damage output. If you want to level quickly, the DPS is more important. If you want to solo hard mobs, survivability is more important.
Survivability In ESO can mean two things. Healing or pure toughness, or preferably both. If you can balance your character to be able to both take a punch and deal out some damage, you’ve got yourself a soloer.
As an example. My main character is a Templar. I have tried to balance him as good as I can towards solo play. He uses Heavy Armor, this greatly improves the damage he can take. Since he now can take some damage, I have chosen to Dual Wield instead of using a shield to do more damage. I have gone down both the Dawn’s Wrath (Ranged Holy DPS) and Restoring Light. This gives me spells to do Damage from afar and slow and root mobs, and it gives me healing powers. I have chosen not to go down the Aedric Spear skill line as I don’t need more melee skills, as I get enough of those through the Dual Wield Skill line.
These principles can be used when building any class. Think of what combination of armor, weapons, and skills will best suit your character and playstyle, and you’ll be good to go.
More specific builds and tips for each class will be posted in the Class Guides Section.