The Toad/Nomad feel pretty open to me, and I think the TinyMight 1 and 2 are too but I haven’t used them.
The Firewood 7 isn’t too restricted and might work, but doesn’t feel as open to me. I’ve heard that the Firewood 8 is a bit more open but it still has a narrowed glass adapter so I’d guess not the most open draw around. They’re also hybrid heaters, but the 8 is supposed to lean more toward convection.
The Roffu might be worth checking out, but I’m not sure about its draw resistance. The thread about it probably has that info though.