Wow, an entire forum I didn't even know existed o_o
For the longest time I participated in AdvanceShipping discussions on Bulbagarden, until some rival shippers who happened to be moderators trampled over a few of us (myself included) in a banhammer rampage.
It's really nice to see a forum of this nature spring up on PC, though. :)
I'll try to participate as much as I can! :D
As for the topic, then.
Why do you like AdvanceShipping?
I'd say because its the most realistic choice for me. I don't like PokéShipping because of its overblown popularity for arbitrary reasons, as well as Misty's attitude towards Ash. I don't care for ContestShipping for similar reasons I listed for PokéShipping, replace Misty with Drew. I think that AdvanceShipping is a mutual relationship because of the episodes Ash and May shared. He helped May in contests with encouragement, shown particularly in her first contest, where she faced off against Drew. I have a soft spot for PearlShipping as well simply because of the relative dynamic it shares with ADV, even though Dawn is just as dense as Ash at times.
tl;dr SatoHaru just makes some good ol' logical sense to me. Love-hate never really cut it for me, sadly.