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

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I love my Philips air fryer. Quiet. Doesn't take up much space. Menu is easy to operate. Easy to clean. I don't know how true it is, but I read somewhere that they invented the air fryer and own several patents on it. https://preview.redd.it/ej1nkc067r6h1.jpeg?width=679&format=pjpg&auto=webp&s=174608a1174ed43e719ef16f87bb6d8fd026ef9b [https://www.amazon.co.uk/Airfryer-2000-4-2L-technology-touchscreen/dp/B0CWNXKY9B/ref=sr\_1\_1?th=1](https://www.amazon.co.uk/Airfryer-2000-4-2L-technology-touchscreen/dp/B0CWNXKY9B/ref=sr_1_1?th=1) The one at the above link doesn't have a viewing window like the picture. Maybe they don't have that version in the UK/EU in the 4.2L. I kind of like that feature so I would recommend trying to find that version if it's available there, or get that 6.2L one that comes with the window.
If avoiding PFAS is the main goal, the Ninja Foodi Dual Zone AF300ANZ is worth a look ,ceramic coated basket, so no PFAS concerns, and it's a proper basket-style unit (not a glass/oven type). For the "keep it simple" brief, the Philips 2000 Series 4.2L is dead easy to use, fewer presets, smaller footprint, your dad won't be battling a wi-fi setup screen. The coating isn't ceramic but it's a well-tested unit from a reliable brand. [top7kitchen.au](http://top7kitchen.au) has a rundown of the current top air fryers with current pricing if it helps narrow it down.
I am happy with Philips 2000 series.
Very happy with my Philips 2000 series airfryer. Easy to use, easy to clean, doesn't take up much space in storage. A single basket is enough for what I need it to do. The complete machine feels very sturdy. Friends of mine have a Ninja. No complaints there either.
I think the best would be a single basket. Philips is easy to operate and easy to maintain. the buttons include various cooking options eg chicken, toast, grill. Go for Philips Series 2000 or Series 3000 Series 7.2L
I’d highly recommend going with Philips for airfryers. They have a brand history and their parts are easily available if required any replacement. One best thing about this bran dis the maintenance and durability. I've had mine for over 8 years. If you want to cook two different things at the same time, the dual stacked models are a great option - they save space since the drawers are built vertically instead of side by side. If you only need a single basket, the Philips 3000 Series (7.2L) is a solid choice, or you can also look at the Philips 2000 Series for a more budget-friendly option.
I have the Philips 2000 series. It was surprisingly cheap on Amazon and while it does have an app (pretty sure it’s just to show recipes), operating it is fully manual. Literally choose temp and time and click start.
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

Ranked #1
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