Fastest way to get data from Multiple lists across multiple site collections

HI

I need to get data from multiple lists which spread across 20 site collections and need to show it as list view.

I have searched on internet about this and got some info like options would be to use search core APIs or BCS but not sure how exactly it can be used . In case of search data won't be accurate depends on Crawl and don't know how BCS can be used.

if anybody can provide ideas it would be help.