I have status with both (senator and gold) and use both quite a bit. There is not much to choose between the two in terms of service in the air. Both are good. To the points you raise though:
– LH are routinely more expensive than BA on european routes, but can be cheaper on long haul business class (especially if you factor in Swiss). LH short haul business class is very expensive, and not as good (in my experience) as CE either. They do the middle seat free thing, but don’t change the seat configuration – so its essentially economy class seat, but with no-one sitting next to you. In flight F&B isn’t as good in short haul on LH, and LH lounges can be very basic, even in Frankfurt, where they can become really, really busy.
– LH only have one flight a day now to Edinburgh so you have less choice when things go wrong – and you are bound to have longer connection times
– Frankfurt is not the easiest place to make connections. T5 is a doddle (and you will only do security once on your return trip when you leave EDI. In Frankfurt its quite common to go through security twice – so on your LH itinerary that could be up to 6 security scans per trip)
– The main reason to fly LH over BA used to be timekeeping and reliability as BA domestic flights are the 1st to get delayed if things go wrong at LHR. This seems to be a thing of the past now with T5
– When you have plenty of miles, you may find there is more flexibility to redeem on LH – and of course you have the fab 1st Class Terminal at Frankfurt which is excellent.
– *A has more options than OW, but often the airlines aren’t as good.
One last thing – you dont mention where you live, but if you are based in Athens, the qualification tiers for status within BA are much lower (and easier) to retain. Based on 80tp each way on a CE /qualifying domestic itinerary you’d get to the gold threshold with only 5 return ATH – EDI trips. With LH you’d be looking more like 10-15,