Brady is the standard for high quality industrial vinyl tape printers. The two units large enough to print arc flash labels are the Globalmark series and the Powermark printer. Brady guarantees their labels for 5 years in direct sunlight, and they offer a number of chemical resistant label materials depending on your environment. They are higher priced than many other competitors but the labels are longer lasting and the money is worth it.
These Brady printers are heat transfer, but the thermal ink ribbon is contained in the printer rather than being part of the tape, as it is in low-end thermal printers like the Dymo Rhino series and similar. Once the label comes out of the printer heat and pressure will not affect it.
The firm that did our arc flash labels 4 years ago used a Brady Powermark printer, and I have a Globalmark 2 Color & Cut model that I have printed over 3000 labels for lockout/tagout identification of motors.
I do agree that engraved Phenolic tags look more professional, but they too will degrade after 20 years exposure to traces of chemicals and to sunlight. For me the flexibility of having a printer on my desk connected to my computer is better than having to send out for phenolic tags, The other aspect to consider is that 70E currently requires an arc flash study every 5 years, which in many cases will require a lot of new labels every 5 years. Since Brady guarantees their labels for 5 years and we've seen them last 10 years in our plant and still look new, it seems like a pretty clear choice to me if you're going to do enough volume to justify the cost of the printer.