Soldering does not need a big flame but a focused one. A gas torch with a jet flame blows the butane out under pressure, so you put the heat exactly on the joint and not on everything around it.
For soft soldering on a copper pipe that is more than enough. The choice lies in the flame strength, whether you can lock it, and whether the nozzle reaches the pipe.
A yellow flame heats a wide area and leaves soot on the copper, so the solder bonds less well. A blue jet flame burns clean and puts the heat on a small area, so the joint comes up to temperature quickly and the pipe around it stays cool.
This category holds gas torches suitable for soldering work: models with an adjustable blue jet flame, a lock and a size you take along to the job. All refillable with butane gas.
The same torch also does other work where you need focused heat, from heat-shrink tubing to seized bolts. If you are after the heavier kitchen models, have a look at the gas torches. If you just want the blue flame and nothing more, those are with the jet flame lighters.
When comparing, look at the flame strength, whether it can be locked, the length of the nozzle and the tank size. If the flame stays uneven, the gas is usually the cause: that is in lighter not working any more.
If you mainly work on pipes behind a panel or in a crawl space, pick a model that stays upright when you put it down for a moment, and check how far the nozzle sticks out of the body.
