Reddit is a social platform that has become the meeting point for millions of people every day. Reddit allows its users to debate about any opinion or news, by posting comments and answers to previous comments of other users. Our aim is to analyze real-world debates from Reddit to check what are the winning positions and the level of discrepancy between users. To analyze the agreement or disagreement between user comments in Reddit debates, we propose an argumentation based analysis that represents a debate as a two-sided debate graph. In this graph, comments are divided in two groups, the ones that agree with the root comment of the debate, and the ones that disagree with it. The edges of the graph represent disagreement between comments of the two groups. Finally, we model the problem of obtaining the accepted comments of the debate, as a valued argumentation problem, where comments are arguments, the attack relation is the disagreement relation, and values for arguments are computed from the votes of users to comments. The accepted comments are computed using the ideal semantics of abstract argumentation. Next, the agreement is analyzed comparing the comments accepted from the two sides of the debate graph. To test our system, we analyze a test set of Reddit debates where we obtain the accepted comments from both sides of the debate and we compare the differences between both sets.