My friend that works in a developer company said to me
1. don't get top floor,
2. don't get below any type of sky roof sky lounge sky anything,
3. and don't get near pump

For 1&2
For after VP, if roof leaking or any sky facility leaking, it will be under condo management to resolve. If only affect Ur unit but will need to spend 100k of sinking fund to fix.. you think they will make it quick or shake leg and delay as much?
Need all committee to agree to spend that 100k to fix the top floor, most likely they will quick fix and it will be a recurring problem if haopen

For 3, any pumps grow noiser and more vibration by age. Today might be silent after 5 years might be like a vacuum cleaner. Too costly to change, so u just have to suffer.

For 3, the pumps can be noisy from day 1, just like those at my place. Luckily the pump house is stationed at ground floor and away from the nearest units.

Yes any pump can be noisy, but most of the time la when it's new you won't hear the pump. But when after 5 years without proper maintenance it will vibrate and make some loud noise. Which you won't know until it's too late later on

can u suggest how far away is good enough to avoid the noise? is lower 2 floors and not directly under the tank good enough?

This I cannot answer as there are lots of variables involved - size of pump, thickness of walls, layout...