I would say the seats in economy class for both are similar. CX seats feel like they have a bit more padding which is nice. Service wise, CX is a little bit better than BA in economy. Service in BA economy is adequate and even sometimes good. Service in CX economy is consistently very good. The food on CX is tasty and they offer some very nice snacks during mid-flight including noodles, sandwhiches, candy bars and peanuts.