AUH and DXB are my home airports, and this has happened to me a few times.
I’ve only been re routed on EK when UL cancelling flights or having delayed flights. BA flat out refuse to rebook onto EK with delays or cancellations.
I have however successfully claimed back the cost of taxes and reciprocal Avios for a redemption flight in EK F, as well as my UK261 compensation when I was denied boarding (wrongly) and they tried to rebooked me on Gulf Air. They didn’t fight this at all.
In all other instances I’ve been rebooked on Qatar or moved to a later BA flight with compensation easily given. A win for me - as I’d rather fly QR than EK anyway.