The SV650 is often the most obvious choice, but in all fairness, there are others.
LIGHTWEIGHT SPORT STANDARDS:
The 4-valve liquid-cooled DOHC inline-four Suzuki Bandit 400 is not imported to the U.S. anymore, but it was(is) one of a kind. Unfortunately, it is out-classed in every way by the SV.
There has never been a 525cc inline-triple Sport Standard.
The 4-valve liquid-cooled 90-degree DOHC V-twin Suzuki SV 650 made the Honda Hawk obsolete, but the SV lacks the Hawk's single-sided arm.
The 2-valve air-cooled 90-degree SOHC V-twin Ducati Monster 696 is another option.
The 2-valve air-cooled 45-degree pushrod V-twin Buell XB9 (984cc) Lightning is not my favorite, but it could work for some.
MIDDLEWEIGHT SPORT STANDARDS:
The Yamaha FZ6 and Honda 599 are 4-valve liquid-cooled DOHC inline-four Sport Standards, but they suck for some of the same reasons that 600 Supersports suck on the street- like a tepid torque peak at an elevated rpm.
The 4-valve liquid-cooled DOHC inline-triple Triumph 675 Street Triple looks like more fun than giving two toys to three kids.
The 4-valve liquid-cooled DOHC 90-degree V-twin Aprilia Shiver SL 750 looks like a real winner.
The 2-valve air-cooled SOHC 90-degree V-twin Ducati Monster S2R 1000 is another option.
The 2-valve air-cooled 45-degree pushrod V-twin Buell XB12 Lightning is not my favorite, but it could work for some.
HEAVYWEIGHT SPORT STANDARDS:
It's been a couple of years since the 4-valve liquid-cooled DOHC inline-four MV Agusta Brutale has been made in a 750 version, but it's still a good bet.
The 4-valve liquid-cooled DOHC inline-triple Triumph Speed Triple 1050 is the current rendition of the original bad boy. A little porky, but more powerful than ever. Truly unique.
The 4-valve liquid-cooled DOHC 60-degree V-twin Aprilia Tuono lacks for nothing.
The 4-valve liquid cooled DOHC 90-degree V-Twin Ducati Monster S4R (1000) is also at the top of it's class.
OPEN CLASS SPORT STANDARDS:
The 4-valve liquid-cooled DOHC inline-four Kawasaki Z1000, the 4-valve liquid-cooled DOHC inline-four Honda 919, and the 4-valve liquid-cooled DOHC inline-four Yamaha FZ-1 are three options, but I'm not a fan of any of them.
The 4-valve liquid-cooled DOHC 75-degree V-twin KTM 990 Super Duke and the 4-valve liquid-cooled DOHC inline-four MV Agusta Brutale (910 and 1078) look like winners.
OVER THE TOP SPORT STANDARDS:
The 4-valve liquid-cooled DOHC inline-four Suzuki Bandit 1250S looks promising.
The 4-valve liquid-cooled DOHC inline-four Suzuki B-King looks very competent. It doesn't look quite as bad in black. Maybe it would clean up a little with an aftermarket exhaust.