I always stick with Bosch. Although I didn't realise how much some car batteries are. The battery failed on my wife's 120d the other day so I had to get a new one. Told her it would be about £80. How wrong was I! Nearly fell over when the bloke in the shop said £172! The cheaper one was £150 but I still went for the Bosch. 4 year warranty with it as well.