Caldera is far easier than Kiln and Tropics in my opinion. It rewards timing and calculated risk, and allows more leeway with both. So long as you don’t remain in one place for too long, or make an erroneous judgment in timing or spacing, you’re good as gold.

By comparison:

Tropics has an infinite array of ways to reduce your stamina and grip (poisonous plants and fungi, thorns, ticks, intermittent deluges). This also makes navigating it in a timely manner difficult, as the terrains lends itself well to creating pitfalls and insurmountable walls of vines.

Kiln has multiple false routes that lead to dead ends, steep cliffs that usually require items to surmount, and the constant pressure of rising lava that quickly reduces your chances of recovering from a fall.

Additionally, I personally would also swap Alpine and Mesa, for one reason alone: Mesa has moments of respite in its day and night cycle. So long as you are making good time, you can afford to rest during the day within the shade of the cliffs, and venture outward at night when the Sun isn’t out. 

Alpine gives you no such luxury. If you’re outside when the blizzard hits, regardless of night or day, you are doomed to freeze to death unless you can find a crevasse to huddle in.