Honestly, there's many viable high-end Tamer builds, each with their own unique strengths, benefits and play style.
The Disco/Tamer is pretty powerful in group settings or solo against any foe that is vulnerable to Discord. They can use their Disco to really buff the damage output of a 120 Chiv+AI pet, or stack a ton of debuffs on a boss with Disco and a RC+AP Fire Beetle/Frost Mite, to make the boss melt like butter to a group. The Disco/Tamer dishes out almost no damage himself, but really amplifies the damage of his own pet and anyone else. They run Taming Mastery with Consume Damage to make their pet really tanky too. It doesn't require expensive gear for this build, either a high MR Mage Suit or even a high Luck suit works fine on them.
The Death Ray Tamer/Mage

is really powerful too, especially when paired with a 120 Disco+CB pet (i prefer Triton, but Cu Sidhe works too if you want mountable). The pet is basically just to tank the enemy and debuff their Energy Resist, so the Tamer can melt the face off the mob with Death Ray, Chain Lightning, or E-Bolts. The Death Ray Tamer/Mage

himself dishes out far more damage than his pet does. Since the Death Ray Tamer/Mage

has 120 Magery/120 Eval/120 Vet, he also has quite a bit of utility with powerful Blesses, Curses, Para Fields, and 100% rez chance of players or pets, and his pet does provide Disco+CB, making the enemy take more damage (especially Energy) from anyone else as well. They run Magery Mastery most of the time though, so the pet isn't quite as tanky without Consume Damage. Since Death Ray itself is not affected by SDI, this build doesn't
require a high SDI suit, but it still helps for Chain Lightning/E-Bolts in those situations when channeling Death Ray just isn't feasible due to movement or area damage. Human is recommended, for getting into Wraith Form with scroll to leech Mana back.
The SW/Tamer is also pretty powerful. With a high SDI suit, the SW/Tamer can whip out some good AoE damage with Thunderstorm/Essence of Wind, or single target execute damage with WoD, while also having good healing capabilities with Gift of Renewal and Arcane Empowerment (which buffs heals, allowing Greater Heal to heal for 90-100 per cast). They usually run Spellweaving Mastery, so aren't using Consume Damage for a tankier pet, but they do have pretty powerful heals to compensate for that somewhat. The SW/Tamer is pretty dependant upon both a high SDI suit, and other players (for a max level Focus) to operate at peak power.