I recently found that DBS invest-saver (RSP) now offer REIT ETF. (Nikko AM-StraitsTrading Asia ex Japan REIT ETF ) is it wiser to go for the REIT ETF or the STI ETF ?

Neither: Both are highly concentrated in terms of exposure and i doubt will offer enough diversification. If you'd prefer to automate your investments, you may want to consider a robo-advisor instead

Both are different asset class so both have different risk involved. Choose based on your outlook and your preference

What are the differences:

STI : tracks singapore growth progress. If you are confident in SG growth, DCA it

REIT ETF : A portfolio of reits in Asia (excluding Japan). it tracks the progress of reits performance in the Asia region. It is more diversified than STI because it covers more countries. Reits can be seen as more stable as the profit came from rental income(in which pricing has been confirmed due to lease agreement).

REIT ETF could be seen as a dividend income etf while STI is like growth etf

Personally, I would choose neither of them.

Cost: cheaper to DCA STI

Returns: cost is compounded from buying reit etf. I could buy a good REIT with possible higher returns.​​​

Depends on yr portfolio. If u alr have investment in pty alr, then maybe u can go for STI. Otherwise REITS can b a good option especially S REITS.

Both sti etf and reit etf invest in different things. Therefore, it depends on what you are looking for. STI etf invest in the top 30 companies in singapore while the reit etf invest in only reits.