Everyone keeps talking about lengths. There are far more variables in what makes a good running boat. #1 is the driver. Hull design, balance, staggard or side by side, drives (a #6 boat is gonna be different than a bravo boat), engine power, and so on.
Id put a single engine 28 pantera up against some boats 4-5ft longer in rough seas.
My honest opinion, take a comparable powered 38 cig, and a 38 or 42 fountain, and run them in rough water, who gets to the card stop first will depend on the driver. My boat can go from riding like a turd in rough water to skimming smoothly across the tops of the swells, depending on how "I" run the boat.
In this market there are some great deals. If you had a number in mind to spend, i would factor in the power package, trailer, and let the numbers make your choice. If you had a choice of a 525/xr gun, vs a 700/nxt fountain, for the same dollar, go for the better power package. Either boat is a killer ride.