Both the blues and the blacks are using 1 TB platters now. Blue's only come in capacity up to 1 TB, while Blacks come up to 4 TB. At the same capacity, you're paying extra for the warranty on the black.
If you value the extra warranty at the level of the increased price, then the blacks are a fine pick. Consider though, if the drive fails in like, 3-5 years, will you be happy replacing it with a refurbished 1 TB drive? HDD and SSD both have consistently seen dramatic improvements on that time scale, and it's possible you'd rather just upgrade to a larger capacity drive at that point.
Just don't confuse 'longer warranty' with 'more reliable'. A longer warranty is exactly what it says on the tin and probably not much more. Either way, trust no one and make good backups.