You really don't have a choice between LH or BD as the flights are code-share on BD metal. For some reason, internet booking for the same LH/BD flight is cheaper on the LH web-site than on the BD web-site.

You have to be careful with the exit rows on some aircraft which have two exits side-by-side. To facilitate emergency evacuation, the front of the two exit row seats does not incline.

By the way, if cost is an issue, easyJet will be starting a new daily MAD-LGW service on Sept 3.