what are the best upright pianos?
['Casio Privia PX-160.', 'Casio PX860 BK.', 'Korg B1SP 88 Weighted Key Digital Piano.', 'Yamaha YDP143B Arius.', 'FLYCHORD DP420K.', 'Schiller Special Edition.', 'Yamaha Arius YDP-181.', 'Yamaha U1 by FourStar.']