Is this a question you would like to be evaluated for a project investigation? Or are you asking about how to set up a fair test to answer this question? An experiment could be set up to find the answer. You would need to have the exact same kind of cereal with the only difference being the presence or absence of sugar. You would need to pour a measured amount (the same for each) of milk over the same amount of the cereal, say 1 cup. Then you would need to time yourself for the taking of a photo, say, one every 10 seconds. Comparing the photos would then be the evidence you would need to answer the question.
Another test for which absorbs more milk would be to set up the experiment as described above, then after a set period of time (10 minutes, 20 minutes, etc) pour off the milk that is left and measure what you have. This can be compared to the 1 cup you started with, and whichever cereal gives back the least amount of milk will be the one that absorbed the most. Be sure not to get any of the cereal in the recovered milk: it will throw off the measurement.