The short answer
These two are not competing. YSL Libre is a signature — the bottle you wear most days and people come to associate with you. By the Fireplace is a season, and a fairly short one.
If you are buying one bottle, buy the signature. If you already have one, the $28.56 difference is not the question — whether you want a scent that only works four months of the year is.
YSL Libre vs Replica By the Fireplace: they answer different questions
Libre is lavender and orange blossom over vanilla: bright at the top, warmer as it settles. That structure is why it goes with most things and most weather, and it is the reason it sits at 4.7 / 5 — the highest-rated fragrance on this site.
By the Fireplace is smoky woods and roasted chestnut with a clove warmth. It smells like standing near a fire, which is a lovely thing to smell like in June and a strange thing to smell like in January. It rates 4.6 / 5, and nothing about that number is a criticism of the scent — it is a criticism of wearing it in the wrong month.
Worth saying plainly in September: the weather is going the wrong way for the fireplace one. If you want it, it will sit unopened until autumn.
The flaw in the popular one
Libre's problem is that it worked. You will smell it on other people — in lifts, at dinner, on someone at the next table. For a scent whose job is to be yours, that is a real cost, and it is the one thing that would push someone towards the less obvious bottle.
Whether that bothers you is a genuine question rather than a rhetorical one. Some people want the compliment-getter and do not mind sharing it. Some want the thing nobody else in the room is wearing.
The flaw in the interesting one
It wears closer to the skin than the price suggests. That is worth understanding before buying, because it changes what you are getting: this is a scent for the person next to you, not for the room. If you want something people notice from across a table, this is not it, and no amount of spraying fixes projection that is built into the composition.
Used as intended — close, warm, cold weather — that intimacy is the appeal rather than the shortfall.
How they sit against the $484.67 bottle
Parfums de Marly Delina is also on this site at $484.67, and it is the one people stop you to ask about. It rates 4.6 / 5, the same as the fireplace one, for roughly three times the money.
That is the useful frame for both of these. At $189.99 and $161.43 you are in the range where a fragrance can be a normal purchase rather than an event. Neither needs to be saved for occasions, and a bottle you actually wear beats a better one you are rationing.
So which one
One bottle, no collection: Libre, and accept that other people have it too. Building a wardrobe, and it is heading into autumn: By the Fireplace, worn close, on the cold days it was made for.