I would say go with the Summit and you will not be sorry. I'm not familiar with Ameristep so I will not comment on them. I have used Summit, API and Lone Wolf in the past. I'm now back to a Summit and could not be happier. I can hunt all day in the Summit with little discomfort, it is rock solid and is simple to set up in the dark. I do not shoot sitting down but I would imagine the bar could get in the way depending on the angle of the shot. Summit has great customer service and they also come with an excellent safety harness.