I have been to both, and this is my main outcome.
SakuraconPros: I live only an hour away from Seattle, the only major money issue I have to deal with is gas. The con is also BIGGER, with more cosplayers, meaning more of a variety, which also means more pictures I take. There are more events and guests as well, and the guests are always at least 3 people I really want to meet. And since it's at the same place every year, to me it's easier to find places to get around to, even though I've only gone to 2 Sak-cons.
Cons: The SPACE and the PEOPLE. My worst Sakuracon experience was 2011 when me and my friend just got off an escalator going up to the main floor and there was a crap-load of people. There was also a taped area that you couldn't stand in, so we stood OUTSIDE of it and got yelled at by a security woman. We had to walk another 20 feet somewhere else and stand there so we wouldn't increase the flow of traffic. Stuff is EXPENSIVE there too. I remember going there with $70 and leave with nothing and only bought 4 things. They were NORMAL things too, like a shirt and a plushie. I also felt that there were a bit more "rude" con-goers AND security that year (2011). 2010 was great since it was my second convention, but 2011 was NOT a good experience.
KumoriconPros: In all honesty, I feel more closer to people here as friends (or family, like what nikkioli said.). I like the smaller size since I can get around more. The staff here are AWESOME (while still having to be strict in a good way and organize everything
)! And everything is cheaper as well.
Cons: At S-con, I go to quite a number of panels, compared to K-con. At K-con, I only go to VA's panel, maybe a workshop, an autograph session, and a funny panel (went to Slightly Anime this year.). There just isn't a variety of panels that are in my interest to go to, and with that, I get bored a little easier at K-con. But to resolve this, I always make friends at cons and just hand around with them all day. However, I can also do this at S-con. Also, I have to travel 3 hours to get down to Vancouver and finding a hotel is a pain.