Okay, you want a honest comparison?
Both were typical traditional players of the game and had a decent run in their respective sides. On the fielding front, both were brilliant and held onto to most catches.
Let's get to batting. I'd rate Cullinan slightly higher than Rahane here. Cullinan 's era had some great bowlers and he fended them off pretty well. While I did allude to him being bad vs spin, that's probably on account of his duel with Warne. If you take that away, Cullinan was quite a handful vs India, Pak and even Sri Lanka. It was difficult to dismiss him in Tests. He was the mainstay of the famed SA team ( which sadly didn't win any World titles bar the ICC KO 98) and was equally good in ODIs as well.
Rahane- he should have represented India in more games. Spent the first few years of his career carrying drinks in MSDs team. I like him as a batsman and he was a good test player. Had he applied himself a tad more, he would have been regarded a bit more by the public.What people often forget is that Rahane was a good limited overs players who got sidelined. He had the game, but was unceremoniously dumped from ODIs. On the leadership front, he was a good deputy to Virat. I've always maintained that he ought to have taken over the Test captaincy for a few years after Kohli, but alas it wasn't to be.
Btw
@cricfan123 , the Mark Waugh comparison is definitely far off. Waugh was superior and I'd say his game was better than Steve's too. Steve's aura though was much more and that reflects in the Aussie sides in the late 1999s. For Rahane, if you want to draw parallels, I'd probably go to the extent of Younis Khan. That might be a logical call.