Poky
1248
Depends on how you are going to wear them
IMO neither is a true sports watch, both need to be protected from shocks and extreme conditions.
The steel on 5726 marks so easily and are you seriously going to take that swimming in the sea? You would still have to look after 5726 (I would anyway) so for that reason you might as well go with 5740.
The white gold makes it less conspicuous but you still have the benefit of the weight and feel of the gold. I am not sure if everyone would choose WG because it looks a bit like SS. I prefer something low key in public areas so red/yellow gold is a no no for me.