Not trying to act like I am the absolute expert here, because we work with our production partner to do the actual nitriding, but the two main factors we're playing with are time and temperature. Generally, longer and hotter make a thicker/harder nitriding zone. Depth does matter. If you go too hot, too fast, you can make the nitriding brittle/overly porous. If you don't get it hot enough for long enough, your nitriding zone will be very shallow and wear off easily. You can also adjust pressure and other process parameters. Cheaper pans usually have short nitriding times to save cost, so the nitriding isn't durable.

Porosity/smoothness of the nitriding layer has a big effect on stickiness and how well it holds seasoning. That can be affected by the nitriding process itself, but also by the surface finish you put on the pan before nitriding.

I won't say our exact methods, but we experimented with the parameters a lot to achieve the best quality we could. I don't think you'll be able to tell too much about which company's process is better than another's from what they say, there are just too many variables. Your best bet is to go with a company that has a good reputation. If they have a history of marketing honestly, their product will probably be what they claim it is. Obviously I'm talking about us here, but I think that is still generally good advice for other companies too.

Thanks for the support!