As a semi-regular user of SEN I can confirm that had I ever been surveyed (I haven't), I would have ranked it number 1 in the UK. Admittedly the only other 'small' UK airports I've used recently are LCY and NQY, the former I've had long queues at security twice and the latter charges a fee. But certainly a much nicer passenger experience than the larger London airports and EDI (can't speak for any others!).