Banjul,
This is what I gathered within the past few weeks for my upcoming interview at SIA Cargo in 2006
Pilots at SIA C seem happier than those at Etihad. The forums show that Etihad pilots have a number of complaints while SIA C expats do not complain much.
You need to consider the distance from home, which is in favour og Abu Dhabi. If you take your family with you Singapore may mean long days of separation as the turn around times average 13 days per trip.
Singapore is more civilized but it may be more expensive. School fees are high and the company's assistance covers 60-80%. while Etihad covers more than that. Especiallyif you have more than 2 children ,Etihad are better in this regardd.
Vacation is better at Etihad.You have better freedom of ID travel at Etihad.
AT SIA C this is almost non-existent as you travel on ID 75 of an expensive econ class fare and it does not include a third child.
I believe you have made comparisons of the pay, taxes and other benifits.
You can check this & the other replies against your priorities.
I hope this helps
Good luck
Sam