Really comes down to taste. Are you looking to maybe get into events or organize with some friends and destroy them? Do you just want something to plink with in the house? Are you into any kind of cosplay?
Nerf has a bunch of different product lines that cover quite a bit. Elite is their standard stuff and there's plenty of things in there that run the gambit of competitive to plinking with a few dumb ones that don't quite work right. They also have Doomlands and Zombie Strike which have neat looking cosmetics while also having some decent performance. Mega has bigger darts that whistle and will probably be a bit harder to lose under the couch if you want to just mess around at home. Rival is their actual competitive line that uses round balls instead of darts and generally shoot about 30 FPS higher than dart blasters, not the best for at home fun since the balls will bounce and roll everywhere but if you want to shoot at other people it's hard to beat Rival off the shelf. A lot of the third party stuff like Buzz Bee isn't half bad. Their electric stuff is a bit more annoying since they don't use rev triggers, but they also don't care about safety as much as Nerf and generally shoot harder.
If you have the time, there's plenty of YouTube channels about it. I'd recommend Coop772, he has excessively thorough reviews that will cover and explain pretty much every part of blaster so even if you're just starting he will educate you. Captain Xavier is much more of a hobbyist and doesn't do a lot of reviews, but shows you how hardcore you can get into Nerf as a hobby, and he's just fun to watch.