It was a few years ago so the prices are out of date.
But it's fairly easy to pull some base numbers from Falabella just to start the process.
So just thinking of furnishings for 1 room.
Master Bedroom: 1 King Size Mattress Average price on Falabella - 4000 pesos. Headboard, 1800 pesos. 2 bedside tables, 2000 pesos. Flatscreen 32 TV: 3100 pesos. TV stand, 1000 pesos. Air conditioner: 4000 pesos. Rug (decent quality) 1000 pesos. Safe: 500 pesos. Sheets (3 sets): Average price here for a decent quality of 500 TC sheets. 1000 pesos a pair. Desk: 1000 pesos
21.000 pesos for just 1 room. Now multiply that by X amount of rooms.
And I haven't even talked about the cost of things like a washing machine/dryer, refrigerator, oven, blenders, microwave, multiple ACs (at least 2 more). And then buying plates, forks, knives, glasses, towels,, etc, etc, etc.
And for the record, the prices I posted above aren't even for what I consider "good quality" stuff. That's for Falabella quality things.
(To be fair, you could probably sell things when moving and recover costs but I never factor in a potential as an absolute return on investment. )
And when renting long-term, unfurnished, don't forget that building expenses aren't included in that rent. So factor those in.
If you were renting for years and years, yes of course it's a better deal to go unfurnished as eventually you can/will recoup the costs. But for anything under 3 years, it doesn't make any sense IMO.
ETA: At the time, I was paying about average 1600 USD a month for a 120 square meter. 2 br, 3 bathroom apt, furnished, in a doorman building on Libertador on a high floor. I prob would have paid about 4000 pesos (or let's say 900 USD) to rent it unfurnished. Apt expenses were anout 1000 pesos a month. So about 1150 USD a month. It would have easily cost me 20,000 USD (and honestly, prob more) to furnish the apt halfway decently. So I would have had to rent for 4+ years unfurnished in order for it to have started to be a "good deal" to go with unfurnished.