I agree with most of what you said, but I don't agree with -

应该是I agree with most of what you said,but I don't agree with some of it。这和我不同意你一些话是一样意思。不过这样所比较婉转,而且也是说话的一种技巧和对人的心理的利用。因为人都比较爱听好话,如果先给人一个肯定,那么别人就对你下面要说的不同意之处比较容易接受。