One is the Instant Pot Duo Crisp, which I use mostly for sous vide, pressure cook and occasional air fry.
One is the Foodi Max Health grill, which we like to use with the probe to get perfect results with meats.
One is the Speedi 10 in 1 which the OH enjoys using for instant meals and to work alongside the Foodi Max Health Grill.
This one (AF300UK) has a place for us, the OH really really wanted this one and I always get her what she wants + I batch cook quite often and this will be useful.
How does it compare to the others?
I've tended to think of "air fryers" as that 4th one you've got or the single-draw equivalents... they're after all built with air-frying as the main purpose i.e. small 4L -ish, rapid cooking oven.
But it does seem popular to incorporate air fryer functionality into other appliances like two of the things you've listed are basically multi-cookers (pressure/slow/steam) with air fryer lids and the other is a grill with air fryer lid... the other type I've seen are the sort of microwave sized oven air fryers (sometimes with a rotisserie attachment) which can be more like 10L - 30L in size.
I think personally I'd want an instant pot or ninja equivalent separately to an air fryer but the idea of an air fryer and grill combo seems like it might work for me.