U really cannot compare apple to orange. Oleander, in my opinion, is overpriced at $900k for 3 bedders unless the unit is very well maintained or newly renovated..condo is coming to 10 yrs...lots of maintenance need to be done, and therefore you have to pay quite a sum into the sinking fund. And the layout in Oleander is not exactly ideal..too many corners and odd shapes., 3 bedders might be a little small for a family of 5, excluding the maid. The only selling point about Oleander is its location, no problem in renting out and u save a lot on transportation. My previous flat was very near to that condo, and I really loved its accessibility to the amenities. However, with the other condo Trevista coming up, I am not sure if Oleander will be as popular as before. Interest rate is currently low, and hence it is still sustainable...what if interest were to shoot up to 5%..the monthly loan and interest payment can be quite taxing esp for young working couple. HDB, on the other hand, will be a much safer bet...in the very least, banks are unlikely to seize yr flat if you are not able to pay up.
I was looking for Bishan flat before I bought my TPY flat 6 years ago. And Bishan flat, for some reasons or another, tend to command higher value. Personally, I like Bishan estate, but do not like its flat...dunno why..maybe I find their design too close for comfort. But frankly speaking, Bishan is very well maintained mature HDB estate (already more than 20 years!!) compared to others.
6 yrs ago, pple will say that I paid too much for a HDB flat, as I can top up a bit more to get private condo. Now I sold the flat at high COV and bought a new condo at Bishan..pple will say how come I did not top up a bit more to buy landed. I agree with what gimz63251073 has said "to each on his own"..I commit to the level where I am comfortable. And having said that, if owner is able to maintain his unit well, be it HDB at Bishan or condo in TPY, it will still be salable in future cos of their location