I would say mountain is closest. Design is a bit busier and the mountains have knee pads and no hip zips.
Timberline is like a beefed up mountain with heavy cover on knees and seat. Ascent is like a Tiburon, light and breezy. I have played with but don’t own the apex pants. They have a bit of a grid fleece so I am not quite sure how they stack up.
I am an attack fan. If I were looking at something to replace attacks, I would look at the prana zion. I listened to people rave about them for years and finally bought a pair. Less than a year later, I own two pair of the shorts, a pair of long pants and a pair of convertibles. I miss the attack hip zips and the cargo pocket design but the zions are a level more comfortable to me and seem to perform just as well with less pilling than my attacks. They are also $85 a pair (much cheaper on sale) compared to $140 for attacks.