BB trade-ins are usually lower than Apple's, and its database of eligible machines/devices is not as recent as Apple's. Before I do a trade, I always check BB, MacMeAnOffer.com, CashForYourMac.com, and Apple. If the last three are within a reasonable range of each other, I'll do it at Apple for the convenience, particularly if I want a gift card to apply to a refurb order.
Edited to add: because I like to do trades, my strategy is buy at a discount or refurb prices, thereby closing the gap between the sales price and trade-in offer. Case in point: today I traded my refurb M1 Mac Mini base 8/256 bought from Apple for $589 for a trade of $520. That's the kind of margin I like to see. And yes, that also means when you buy a refurb, it might be a refurbed refurb.