First, you have to figure out what you want. Do you know? Long term, short term, value-wise? Then, compare what they want. Do they want the same? Something compatible with what you want? How honest/reliable are the 2 contenders? Do you trust one more than the other? Then what about chemistry? Laughing is good, but what does the other bring? Usually there is good chemistry with most people you are attracted to, and it can be of such different varieties, it's hard to figure out which is more, but then you have to decide based upon what you need, and also upon what they say they need.
Just my $0.02 worth for today.