Yeah I really like the Thessia artwork, It's my favourite one they have released in a long time. I've always preferred the lithos with white borders over the ones with black borders, though the foil N7 logo that comes on the black bordered ones is cool.
Have you seen the SDCC exclusive ME3 lithos? Liara, Garrus and Tali. They are going for crazy money on ebay:
http://www.ebay.co.uk/itm/MASS-EFFEC...item231ff9b294