Ninja
Foodi Dual Zone Series
Dual zones for smart cooking, but baskets are small.

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I had a reg 8 qt air fryer for a few years. Just replaced it with this [Ninja 6-1 flex basket](https://a.co/d/01RJApPx) about 1.5 yrs ago. I love it. I can do 2 small things or one large thing. There is a slight bleed in temps between the 2 baskets, but not majorly so. Ended up getting my sister and mom the same one for Christmas a year ago. We all love it.
Ninja Foodi Flexdrawer. I use it daily and often even more than once a day. I rarely use the oven, toaster or cooking plates anymore since I have this great AF. I mostly cook for 2 persons but of course can be used for bigger meals as well. I even bake my bread in it. Best purchase in years.
We were recommended the Ninja Foodi FlexDrawer and couldn't be happier. One or two small compartments or open it up for a single large one. We cook everything from a handful of nuggets and wedges to a two-kilo chicken.
I can recommend the Ninja Flexdrawer ones. You can use it as two separate drawers or one big drawer. I rarely use it as one big drawer but it’s very handy to have the option.
The ninja flexdrawer one is awesome. Can I ask why being diagnosed as gluten intolerant means you need to change airfryer?
I would recommend either the Dual Zone or the FlexDrawer. We've tested very similar Ninja models and they've both performed very well and are easy to clean. I would not recommend the DoubleStack. As you mentioned, the rear placement of the fans and heating elements does lead to very uneven cooking (food closest to the back gets cooked much faster). A rating of 1670 W is very typical for North American air fryers. You mentioned that your previous model was rated for 2300 W, which means you're probably outside of North America. Most dual-basket models in the UK, Australia and Europe will draw 2300+ watts, and the added power is absolutely a benefit for cooking speed (especially for dual basket models where two chambers are cooking at once). Lastly, in my experience the plastic smell does go away after a few uses. This is common for most brands of air fryers!
I would recommend either the Dual Zone or the FlexDrawer. We've tested very similar Ninja models and they've both performed very well and are easy to clean. I would not recommend the DoubleStack. As you mentioned, the rear placement of the fans and heating elements does lead to very uneven cooking (food closest to the back gets cooked much faster). A rating of 1670 W is very typical for North American air fryers. You mentioned that your previous model was rated for 2300 W, which means you're probably outside of North America. Most dual-basket models in the UK, Australia and Europe will draw 2300+ watts, and the added power is absolutely a benefit for cooking speed (especially for dual basket models where two chambers are cooking at once). Lastly, in my experience the plastic smell does go away after a few uses. This is common for most brands of air fryers!
Ninja
Foodi Dual Zone Series
Dual zones for smart cooking, but baskets are small.

COSORI
Turbo Blaze 9-in-1 6QT
Quiet, easy to clean, but lacks a viewing window.

Ninja
Foodi Air Fry Oven Series
Flips up to save space, but shallow and air fries poorly.

Breville
Smart Oven Air Fryer Series
Oven replacement; spacious, but air frying and cleaning divide users.

Typhur
Dome
Self-cleaning and quiet, but expensive with shallow interior.

Ranked #1
Ninja - Crispi Pro 6-in-1 Countertop Glass Air Fryer

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Breville - Smart Oven Air Fryer Series

Ranked #1
COSORI - Turbo Blaze 9-in-1 6QT

Ranked #1
Ninja - Crispi Pro 6-in-1 Countertop Glass Air Fryer

Ranked #1
Ninja - Foodi Air Fry Oven Series