Biggest factor too is does one live in base for the LCC? If it comes down to this vs commuting to a legacy, that easily might be enough for the LCC to makes sense now vs one of the big 6 later.

Also, does one have any blemishes on their record (or no degree)? If either of those and one is a senior FO or Jr Ca, it probably makes sense to jump on an LCC offer right away and not look back.