Outside of each, who of quality did Velasquez and JDS beat=???
A bunch of one-dimensional fighters (Mir, Cro Cop, Big Nog, Kongo, Carwin, Big Country, Lesnar) or old guys who are way passed their prime (Mir, Cro Cop, Big Nog). They are both the only legitimate competition that either of them have faced and beaten (unless you count JDS beating Werdum before he fully realized his talent).
Jones has beaten legends like Shogun, Rampage, Machida, Evans, and Belfort, all of whom are better than anyone JDS or Cain beat (other than each other). All of those 5 guys at equal weight at the day of the fight would destroy anyone JDS or Cain have ever faced (themselves aside).
And unlike everyone Cain and JDS have faced, Shogun, Machida, and Evans are all very well-rounded fighters with multiple talents.
Shogun is past his prime. Rampage, Machida, Rashad and Belfort were either close to or in their primes. Cain and Dos Santos would beat them as well.