OK, Ill bite - but on the understanding that my coffee palate is in its absolute infancy...
I currently get all my coffee through Cosmorex, see <<<====== sponsors
My fave blend is Cosmos "Blue Blend" - I find it not too startling straight up and cuts through milk nicely. New to coffee wife finds it a little sharp straight (how she takes it).
My (our) fave SO is Guatemalan Antigua - stunning, smooth, with an almost sweet aftertaste that lingers for ever. Wife loves it straight up and I double it into a 250 ml cup as an extraordinary flat white.
Only other SO tried thus far are Sumatran Mandhelling, Kenya AA, and Monsoon Malabar bought here green and roasted fairly dark by a mate. Ive njoyed all of the above and found the MM very nice...but the Guat still tops it.