Impossible to answer!
They both had their share of shitty albums, most made during the 80s. Let's knock that point out and forget it.
Reed and Cale are two VERY different songwriters and musicians. In fact, I believe that the stark differences between their creative styles is what lead to Cale being forced out/leaving the VU (depending on what story you believe.) Reed, lacking the classical background of Cale, simply cannot match his former bandmate's musicianship. This is not to say, however, that Reed is a poor composer; he simply can't perform at the caliber of Cale.
Reed's lyrics are shock-based, absurd and of the "kitchen sink" school of realism. Cale tends for abstraction and an extremely literary style. Simply put, their lyrics are a reflection of their respective cultures --- Reed writes distinctly "American" tunes while Cale's songs have a very "British" sensibility.
I'd say the standouts from Reed's solo career would be, in order, "Transformer" and "Berlin"; for Cale, in order, it would be "Paris 1919" and "Vintage Violence."
Which one is better? Neither. There are times I tend to reach for my copy of "Paris 1919" over "Transformer" and vice versa. Both are tremendously talented individuals and succeeded in their own unique ways.
Besides, could you see Cale in the position of "Reed the superstar" of the 70s? Hell no!