Gold Coast is going to be the most conveniant location to Ma On Shan via the Shing Mun toll Tunnel, by car, it is a very uncomplex sub 30 minutes route. A small car doesnt cost much to run, especially if most of your drive is nice flowing free way. which Mah On Shan to and from the Gold Coast is.
If you buy a used 3 - 5 year old Toyota Prius Hybrid, road tax is under $1000HKD a year, and 55mpg is easilly realised.
Bus from Gold Coast to Central takes between 38 - 55 minutes depending on the time of day. Its an uncomplicated bus route to get to and from work, and thats about it. Gold Coast has a pretty large expat population living in and neighbouring it, rents are also reasonabl. You can easilly rent a 4 year old place, inc gas under bench oven, is 1200ft2 of spacious 3 bedroom apartment with an included car space, also a sea view, all for $18,500 a month, ie Aqua Blue apartments. they also inc a private Shuttle bus to Tsuen Wan and Tuen Mun MTR, making central commutes a no brainer affair. Just one of many possibilities you have to consider.....
Clearwater bay nearest Hang Hau MTR could also be a consideration, as you are about 50/50 time distance from each others work on public transport, about 45 minutes each from there, less time if a car is used for the Ma On Shan leg..
In my opinion, Clearwater bay and Tuen Muns Gold Coast, Sham Tseng, Tsuen Wan are going to be the least complicated routes to and from work, for the Ma On Shan & Central commutes.