Generally, tapered blades are capable of higher speeds, and squared-off blades push more air for a given RPM and air density. Chord, aspect ratio, sweep, pitch and tip speed (mach) are all major factors when matching a prop to a specific engine application.
Note that most Vickers Viscount 700-series have tapered tips and Viscount 800 series have squared-off tips. The photo below shows an early BEA 700-series Viscount with experimental high-speed tips. Efficiency and noise are major considerations in propellor design, not aesthetics.
