While I am waiting on some information about the bill of materials for my smithy structure, I am contemplating a choice between a two burner gas forge or a traditional coal forge. There are good arguments for and against both.
A coal forge is certainly more traditional. I have some experience working with a coal forge, and I found I like it. The scale (oxidized flakes) that form on the working piece are easier to remove, and coal is cheap fuel. Unfortunately, a coal forge is more expensive up front, the fire takes longer to get started, and most importantly for my concerns, coal makes a lot of smoke, especially at start-up. I want to be a good neighbor and not annoy or choke everyone out. Also, a coal forge may be considered an 'open fire' legally (even though it really isn't). I don't really want to deal with that.
A gas forge is less expensive up front. It does not make stinky smoke (or so I am told). It reaches heat faster. Less floor space is used with a gas forge. Downside - the scale is tougher to remove. The gas is more expensive per hour to operate, but I can mitigate that a bit. And if there is a leak, well... boom.
I think, based on these points, that I may go with a gas forge until I can set up shop in a place that can handle the 'downsides' of a coal forge.