having driven both back to back and currently owning auto, i would say get auto, as its comfortable in city and is much better on highway with lower rpms than manual, auto altis sits at 2800-2900rpms at 120 while manual is above 3500rpms, and its a decent gearbox with good smooth accelerator and a ECT power mode/switch as well. however there are downsides too, make sure the car you are buying has a good auto gearbox that has had proper ATF changes and shifts and works correctly, moreover if a auto develops issues its more costly to solve than the simple manual gearbox.
swap would just be a jaguar and it would be better to sell the car and get a auto one than to try and swap a manual one, as ECU, transmission ECU, Speedometer and much more all would have to be changed with stuff from junkyard and its simply not worth it.
so just keep these precautions in mind, make sure you get a good one and you would enjoy auto more.