UK: Mazda6 2019 vs Mazda3 2020

Hey all, I'm based in the UK and have narrowed down my newest car purchase to the title. I'm really struggling to pick between them as they both look really attractive. They are both priced almost the same, the Mazda3 is £11.7k and the Mazda6 is £12k

Mazda6: 2.5 litre SKYACTIV-G GT Sport Nav+

Mazda3: 2.0 litre SKYACTIV-X MHEV GT Sport

In this regard, the Mazda3 comes out superior as it has the newer X engine. The 0-60 times are almost the time whilst the X engine has a higher fuel efficiency and the newer tech which is described as giving it diesel-like torque. The downside to it however is that it's in the second highest trim available and not the highest trim available like the Mazda6 which means it's missing certain technology such as active lane assist. Also in relation to trims, as it's simply a 'lower' model of Mazda, it doesn't come with cooled seats and rear heated seats which the Mazda6 has. I'd appreciate opinions on how useful those two options are.

Both cars have roughly 80k miles and look in good shape cosmetically. The Mazda6 has an automatic gearbox whilst the Mazda3 has a manual. I currently drive a manual and have always loved manual. All everyone tells me is how they could never go back to driving manual in London, but I just don't feel the same sentiment so I don't really see this a positive for either car. Since the Mazda3 is smaller, it would also make sense for it to be nicer to drive as a manual compared to the Mazda6. Also, the Mazda3 is in the iconic Mazda soul red crystal metallic whilst the Mazda6 is just grey. Mazda3 also wins in terms of running costs ie fuel as aforementioned and also car insurance where the Mazda3 is around £300 less annually. This isn't really a big deal to me but something worth mentioning. Also, based on CarWow videos that I watched, the interior quality of the Mazda6 appears to be simply superior, but the Mazda3 also looks/feels really nice and I'm not sure if this would be something really noticeable.

I'm really struggling to make a decision as on paper the Mazda3 seems to be overall better, but the cooled seats and rear heated seats on the Mazda3 are quite valuable to me so I'm constantly going back and forth. I would appreciate any input.