I've always used Mahle filters, for oil and air, but recently their production is coming more from China.  I'm not anti-diversification, but to me the quality of both has dropped.

I've been researching/trying other brands, and MANN seem to have kept a higher quality as standard.  No objective proof, though various people on the internet have cut up filters and shown the internal and construction differences. Quality of filtration, number of folds, the actual paper, return/flow valve quality, yadda yadda.

MANN have also started including fitting instructions - a nice touch.  Made in Germany, so IMO a safe level of quality for any of your cars.

Your mileage may vary.

Just bought a Green Cotton filter. Mainly because I was offered it at very good price.

I've fitted Bosch filters to both our Fiesta's over the last couple of months, due to being what ECP had in stock. Looking on eBay though, genuine Ford filters can be had for good money, and i'll probably go back to those next time:

 

1.0L Mk8 filter as an example direct from Ford: Filter

For oil filters I always go OEM as they are cheap enough to not warrant going aftermarket. Furthermore, at least with OEM you know you are getting exactly the right bypass rating, anti-drainback etc and of course the quality. 

I currently have a Mahle oil and Pollen filter bought from Opie and fitted this year. I am planning to replace my air filter this year, probably before my MOT in Feb. I'm not sure to buy one from Opie or just go to my local car factors. I have a feeling they stock WIX and Mann filters. For my previous car I installed a K&N panel filter, which I was happy with, however as papers ones are cheap and very easy to change, I don't think it's worth buying one.