I try to discourage people from hiking with a load on low-tops, but I understand the appeal. Its more comfortable. But you have to remember: No low-top will "support" your ankle. I dont like trail runners because they all have EVA midsoles, which in my view are too soft to support a hiker and 30 pounds worth of gear, especially on tough terrain.
How about a mid-height? Theyre about as comfortable as low-tops, but typically have tougher, more supportive construction. Case in point: Lowa's Vento Mid hikers ($160). Breathable leather/mesh uppers, comfortable fit, and a polyurethane midsole that can take a load. Vasque's Kota Mid ($130) have EVA midsoles, but a dual-density type for a bit more heft. Like the Ventos youll find that the Kotas make you feel a bit more stable on the trail.
If you must try a trail runner, try Kayland's Dragonfly ($120). A tough shoe, with a sturdy midsole and construction that can take some trail abuse. Or La Sportiva's FC 2.0 GTX ($140), which is really a light boot minus a top. Very tough, and comfortable.
Come talk to me again when your ankles fold under on you.