If your trips are originating in DXB for DXB - LHR, BA will invariably be cheaper. EK's Y prices are similar to WT+, and EK J prices (outside of current Ramadan/ Eid sales) can be sky high. So from that perspective, you're better off maintaining status on both carriers.

When you get a good deal, fly EK. DXB - LHR r/t J gets you a fifth of the way to Skywards Gold. Agree that BA Gold is more exclusive.

Also, EK's new Y seats and new J seats (which you are likely to get on LHR flights anyway) are good. And there's the flexibility of more flights in a day.