The sticker prices are not comparable, and that is where most of the confusion at this decision comes from.
A resale home generally comes with things a new build does not. Landscaping, a fence, a deck, window coverings, appliances in some cases, and a finished basement are frequently already there on a resale property and are frequently extra on a new one.
New homes are also subject to GST; resale homes are not. Whether GST is already inside the quoted price depends on the contract, and it is a question worth asking explicitly rather than assuming.
Once those are added, a new build that looked comparable to a resale listing often is not. That does not make it the wrong choice — it makes it a different calculation than the one the show home invites you to do.
A build takes months, and possession dates move. If you are selling an existing home to fund the purchase, a slipping completion date is a genuine problem — you can end up needing interim accommodation and storage, or carrying two properties.
Ask what the contract says about delays and what remedies you actually have. A quick-possession home — already built or nearly so — removes most of this risk while keeping much of the benefit, which is why it suits buyers coordinating a sale.