If I was only going to have one gas forge, I would go with a venturi, a properly built and tuned one will be able to heat metal with little scale, and reach welding heats when necessary. The other nice thing with a venturi is the only hook-up you need is the gas, so they are easy to take to demos.
A forced air (blower) forge requires electricity, and generally requires you to match the air flow to the gas flow to get the flame you want. While this can result in a hotter forge, and finer control, it takes practice to get it right each and every time you want to adjust it. also, without the air, the flames can quickly reach 4-6 feet in length, or more depending on gas pressure. this can happen if you are working and you lose power. While the flame temperature drops it is still hot enough to start the roof of a shop on fire.
Good luck
Ken Nelson
Iron Wolf Forge