In terms of future development in Jurong, I would recommend the areas between Jurong East and Boon Lay. I am sure you're aware of the development that is happening in Jurong Lake District right? Somewhere along Chinese Gardens and Lakeside MRT would be the ideal place. However, to get a good unit there, you would likely have to increase your budget as $500,000 can't really get a good unit in that locality. Unless you want to go towards Boon Lay or Pioneer areas.
As for the areas between Jurong East and Choa Chu Kang, apart from Toh Guan area and some parts of Bt Batok, the rest of the areas in Bt Gombak and CCK, the prices are generally lower, and you should be able to get a 3-bedroom unit for under your budget easily.
Hence, it really depends on your comfort zone. You do not want to stretch yourself for your first property, especially you have to pay a 5% Additional Buyer Stamp Duties (ABSD).
I have a 3-bedroom unit, huge 104sqm, within 3-minutes walking distance to CCK MRT, and is only asking $430,000. You might want to consider it.
Do contact me at my mobile 9748 6305 for more info.