Haven't owned either, but here is my impression of each one while searching for a new tent myself.
I like the Coleman Instant Tent, but I don't like that there is no ventilation/rain fly. Coleman keeps saying it doesn't need a rain fly, because the seams are sealed, but I personally want the rainfly so there is ventilation when it is raining. Also, because of the lack of rainfly, when it rains, I think it would drip right down the sides, meaning all windows need to be shut and if you are inside humidity builds up and it will be very uncomfortable on a warmer day/night. I passed on this tent while shopping because of this reason. Otherwise, the size and ease of set up is great.
The Eureka Copper Canyon is a great tent and a great brand, and the only flaw I found in it is the floor is thin and not made from polyethylene. It is the same as the walls, and is thin. I would definitely use a ground cloth and something inside to help protect the floor from any sharp objects.
If I had to choose, I would choose the Eureka if price wasn't an option.
I was looking and decided to go with a Mt Greylock made by Gigatent,
http://www.gigatent.com. It has everything I was looking for and not as pricey as Eureka.
Hope it helps.
Best Regards,
Norm
