The differences between the best arc welders can make all the difference in your career as a welder. Seasoned welders know this very well, which is why they use different welding equipment for different jobs. Most welders who are experienced professionals will have an array of the best MIG welders and the best TIG welders with them to be used on any of the different jobs that they come across during their career as welders. This is true whether they are welding for a hobby or welding as a profession.
The best arc welders can be both AC and DC and use both non-consumable electrodes and consumable electrodes. They can be flux shielded arc welding which is known as stick welding and is a manual arc welding process. It can also be gas metal arc welding, as is used in the best MIG welders. The best TIG welders in USA use argon gas as the shielding agent. Each of these has their own uses and advantages and so should be used according to the work specifications on hand.
While arc welding is used most commonly because it is most economical, MIG welding has deeper penetration, and TIG welding is very versatile.