If you want control, you need something with a lot of thermal mass to resist temperature changes and allow for more even temperatures. Thick ceramic (as most crock pots use) does this well, but the only other thing that really does is cast iron. Regular pots and pans tend to change temperature quickly, resulting in a loss of control.
Crockpots don’t generally get hot enough to scorch much of anything, at least not so long as it has any sort of moisture content. My wife has done the soda thing in hers on a few roasts and it’s never had a problem.
If you want to go stovetop, you really need a Dutch Oven.
@Tropical_Willie I’ve seen quite a few crock pots that only heat from the bottom as well, like the one I have. The real secret is that the (thick) ceramic distributes the heat evenly, thus the crock gets just as hot at the top as it does near the heating elements. Good, thick cast iron does the same thing, though considerably slower.
Aluminum, the second-best metal for computer heat sinks after copper, also distributes heat evenly, but generally loses it rapidly. Given the ratio of volume to surface area and how that causes the sort of temperature variations you seem to want to avoid, aluminum only really works for griddles and shallow pans.
Stainless steel is prone to “hot spots” unless it’s copper-clad, and pretty much anything less than 1/8” thick is prone to temperature fluctuations.