The new Nerf Rival series has many impressive, competitive options to choose from. Knowing what playstyle you prefer and your price range is the ultimate deciding factor. Some Nerf players also differ in the level in which they play, some have tactical gear with pockets for extra magazines and speed-loaders while others simply use what they can hold.
The Nerf Rival is not for the low-budget non-competitive Nerf fans, as the Rival series is aimed at more competitive gameplay. However, there are still great offerings if you want to use the Rival blasters; for example, the NERF Rival Kronos Outdoor Blaster. The Kronos is a sleek pistol-style spring-action blaster that boasts Rival accuracy and performance, while also being the least expensive of the Rival line.
If you are interested in a more competitively viable blaster, without breaking the bank, the Nerf Rival Phantom Corps Helios XVIII-700 would be your best bet. It has a magazine, so if you want to carry extra ammo in a easy and quick to reload way. Although it may be hard to carry the extra magazines without holding pouches. The Hades and Artemis have a high capacity, but must be reloaded by hand because they have integrated ammo compartments.
If you have a thirst for competition and power in the Rival series, then you want to go after the battery-powered flywheel blasters. The Hera is the least expensive, and it receives magazines, which allows you to keep more ammo stored in pouches. The Nemesis is next, and it is one of the two full-auto Rival blasters, and it is a powerhouse. It is hopper-fed, which means it doesn't accept magazines, but it does allow for a much larger capacity. The final blaster to mention here is the Khaos, the magazine-fed full-auto machine. It has the benefits of magazines, full auto, and high-capacity. (Although the electric blasters require batteries there is a very high-quality NERF Rival Rechargeable Battery Pack that I heavily recommend if you purchase an electric blaster.)
Nerf guns are for blasting Zombies only and should always be used with care and eye protection!