Is a resale DBSS worth buying or should I just wait for BTO? Am looking at staying near Tampines MRT. Only viable option seems to be DBSS central 8 which is more expensive than normal HDB.?

This one will depende on your timeline. If you don't need to move in urgently, a BTO is probably a better choice. Yes there may be failed ballots, a construction period, etc., but the lower price point means you'll probably see better gains.

Nothing against DBSS, but these are pricier than normal flats and, like other resale units, there isn't as much upside potential as compared to a newer flat.

That said, this is all not relevant on the pure home-owner side of the equation. If this is the priority, then a DBSS could be more justifiable, with its better finishing etc.