Cordless!! Most of the vibration in a trimmer comes from the motor and the fact that a single cylinder engine in naturally unbalanced.
There are many options out there that would do all that you need as well as some having versatile attachment options.
If you prefer to stick with gas-powered, you need to look for something that is specifically marketed as low vibration. You might also benefit from anti-fatigue gloves that are designed to reduce vibration.