Good Afternoon,
Thanks so much for getting in touch with your query. We consider Malaysia Airlines a reputable flagship carrier, they are rated on SkyTrax as a 4* airline which you can view more on here >> https://skytraxratings.com/airlines/malaysia-airlines-rating. Our experience of them to date is positive and we have run this tour using Malaysia Airlines for many years and they use more modern aircraft in their fleet from Heathrow to Kuala Lumpur. Hopefully some members on the forum will be able to share their experiences too.
In the meantime we wish you a wonderful holiday and if there is anything else we can help with let us know.
Best wishes,
Just You Team