I have several.
If you want one for cooking, I'd recommend an electronic one. I like mine because it's set it and forget it. It has a bunch of fail-safes on it to keep it from blowing the lid off, although I'm sure if it popped the valve off it would still make quite a mess.
I also have a pressure canner that will hold 7 or 8 quart jars, I forget which. That one has a gauge that needs to be checked for accuracy periodically.
Then I have a couple of smaller stove-top models. The one I have in the house will hold pint jars and also smaller sizes, so I'll be able to use it for smaller batches of stuff when I start canning again. It's also small enough to use for cooking. That one, and the smaller one in the motor home, both have weights on the cover that regulate the pressure by releasing small bursts of steam that's forced through a small hole in the lid where the weight sits.
I have a vintage book called Pressure Cooking is Pleasure Cooking. If you can find it, it's a good one IMO.
It's very easy to overcook things in a pressure cooker because they will cook things fast due to the increased pressure.
I haven't used any of my PCs in a while, so now I need to drag them out and cook something.