If you are looking at light duty arc welding on a 240 volt supply, then a great choice would be the Miller 160 sti arc welding inverter machine- it's extremely affordable & incorporates a number of features such as; Hot start and arc force, which stops your electrode freezing. What is more, it's generator friendly requiring only 5.5 kw to power it.
For more industrial applications, you could look toward the Ewm Pico 160 CEL (240v) & EWM Pico 162mv (110/240 volt) German built inverters to run electrodes up to 4.0mm. Or view the range of arc welding machines here.
If you're restricted to 415 volt input supply, the Miller STi203 (415v) is heavy duty carryable inverter weighing in at 13 kilos. We like an incorporated feature called DIG. This allows arc characteristics to be altered according to the level of weld penetration required. A 7018 low hydrogen rod for instance would run smooth, whilst a 6010 pipe electrode would benefit from a more penetrative setting.
The key to buying a stick welder is building a specification: Assess your input voltage limitations if you're on site, what is maximum welding rod size you will be running and is the duty cycle of the machine important. Are you welding all day or just odd jobbing?
Remember a 110 volt input will limit your output amperage. Ask the question; Have you got access to 16 amp or 32 amp 110 volt power? This will determine what size welding electrode you can run.