I prefer heat cable, it may cost more but you can just add a few coils for more heat or remove some for less. It is also coated in a fire resistant material. I use both for different things, but whenever I build racks or anything I always pic up heat cable for it. The heat tape heats up fast and cools down fast IMO at least in my experience. The heat cable seems to stay warm after turned off for a while making an on/off tstat work better. I wouldn't use an on/off tstat with heat cable unless I had a rheostat to help maintain temps from fluctuating too much. At least that's what it was like with the last bit I used.
Different strokes for different folks. You will just have to use both and decide which you like better...
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