I can't believe Kallis's bowling is being compared to Botham's at all, myself - Botham was quite easily the better bowler IMO. Kallis was by far the better batsman though, so the poll is again fairly even.
You'd probably have to say that Kallis is a better player - he's one of the top 5 batsmen of his time and, at times, has been a frontline bowler in his own right. Botham never really reached the level of "great" with eiher bat or ball, so he's not quite as valuable as someone who commands their place as a great with one discipline and still contributes with the other, IMO.
But, as an allrounder, Botham comes out on top for mine. Kallis's bowling, particularly as his career has gone along, has declined quite a bit, and it often doesn't even factor into the selection of the test team. He has only had short periods where his bowling has really been anything of note - so as an allrounder, I'd go with Botham.