Where is the best place to sell new phone in singapore?

Don't sell to phone shop or online drop off & pick up buy back phone shop, 98% are grimmick stated perfect condition used phone price as stated will never be honour. Even they have check though your phone without any technical issue, they have something to say to cut your price down by at least 40% and now even worse during pandemic. What I have observed not only phone but also buy back on other electric gadgets and I have being in this line for too long to know that. I have being patronize one phone shop very honest about back buy price but recently one of their staff was using this trick on me too.

My advise is if you have time to meet up with buyers sell it at carousell, the only you must take precaution is to keep the record of the phone just in case someone used your phone to do illegal things

Based on my most recent experience of selling a phone, it seems the neighbourhood ah beng stores in Ang Mo Kio and Toa Payoh central do take phones in at a higher premium than many of those exclusive retailers for the telcos (SingTel, M1 and Starhub). There are at least 10 of such shops so you could walk down the whole stretch to negotiate for a better price.

https://www.reebelo.com/ is also doing buyback for new phones.

Trade in at Singtel! A friend of mine got quite a good price for his Note 9 he won from a lucky draw.