Need a new armchair - any advice?

I need a new armchair. With lower back problems for over 10 years now I have been using a swivel armchair which has seen better days. It now needs replaced and I've tried several types. The most comfortable one I've tried is 'Stressless'. Does anyone have one of these?

I just bought a 'Varier' kneeling chair for sitting at my desk and I can recommend one of these. Good for posture. However, the 'Varier' armchairs are too expensive. Starting price £1329...

Any help would be much appreciated as I want to get this purchase correct.