I have a Otter insulated cottage. I previously had a non-insulated Otter cabin but when I wanted to upgrade to insulated the cottage size was a better fit for my usage. The cottage is slightly wider than a typical one man which I desire and I personally would not go smaller than this. You could squeeze in another person but unless it would be a child I would not plan on this.
You can shave a few pounds with another brand generally due to the tub being less robust and lighter in weight. Generally the Otter’s tub is beefy but if you are not planning on dragging your portable behind a atv or snowmobile then almost any brand/model tub is sufficient. If I have too much gear in the tub of the cottage then it still gets pretty heavy to move it in or out of the bed of my truck by myself. It is much more manageable if I have minimal to no gear in it while loading or unloading. If it was not as cumbersome to pick up by oneself then the weight would not be as much of a issue.
I typically only fish one hole. I would say that would not want anything smaller than the cottage for 2 holes, with livescope in one of the 2 holes and a heater. I suppose you could drill a 3rd hole close together for the livescope but it gets cluttered pretty fast. Along with width I would also pay attention to the interior depth inside (fishable area) if looking at other brands/models. I do not consider the Otter Cabin to be very deep.