Functionality and storage space mostly. The convienence of wanting to be completely topless and having the ability to do that in a matter of 5 mins or less. To be completely topless you have to remove the entire trek top. PAIN. And to mention, the sunrider feature of a soft top is much larger than a trek top, by about a foot, so your rear occupants can enjoy it too. You have more storage space in the rear, and I carry a lot of camping supplies and do not like to use my back seat. And, to be honest the trek top was just played out for me. It's a great top, don't get me wrong, it just wasn't the look I wanted anymore for my JKU. I appreciate the factory soft top for what it does, in its ease of removal.