Well, they are two completely different products to begin with.

BA World Traveller Plus is Economy Class with a slightly better seat. It is by no means a business class product: No separte check in (thought Online Check-in is pretty good), No Lounge, Same Meal (thought word is you get a small real glass with the tryap - whoopdy-do!) If you compre it to business class, you'll be sorely dissapointed. If you compare it to economy class, you'll be pleased.

LH Business class - well I can't comment on the long haul, but it's a business class.

However, if it's a case of thousands of dollars to be saved, well, that's up to you, but I'd probably opt for LH.

Just noted you're a 1K at UA. Don't forget you can use your SWU's on LH to upgrade to First! Oh, and you'll get MILES that count to 1K status.