When I was a kid, more specifically in the 1980s, Diamondback BMX bikes had an above-average reputation around the elementary school. They weren't top of the heap, but they weren't cheap department store bikes, either. Today, Diamondback (like a lot of bike brands) is just a name owned by a bigger company. As best I can tell, they sell the Diamondback brand into the low-to-midrange price/quality range, which I'd say is where your price point puts you.

As for making comparisons when shopping, I would pay more attention to components than the name on the frame. Mass-produced frames are generally built to a price point by a handful of Chinese/Taiwanese companies. Bikes in the same price range, even from different brands, may have been built from the same materials by the same people in the same factory. To help you differentiate between models, check the shifters, derailleurs, wheel hubs, and the like. The more of them that are made by Shimano, the better. (Shimano's not the only maker, but even their less-expensive stuff is pretty decent quality, and they may be the only "top tier" manufacturer you'll find in your price range.)

And seconding something that's already been mentioned, buying at a bike shop is preferable to buying at a big box store. Odds are much better that a bike shop will assemble and tune the bike properly. Competent assembly will make just about any bike rideable, but careless assembly and tuning can make even the best bike ride downright awful. And besides, most bike shops will offer post-sale adjustment & tuneup support, which comes in really handy if you don't feel comfortable turning your own wrenches.

As for pros & cons of hybrids versus road bikes... Road bikes are built for speed on paved roads. They'll be light, they'll have narrow tires to reduce rolling resistance on pavement, and they'll generally have drop bars (curved handlebars) so you can crouch into a more aerodynamic posture and cut through the wind. They'll almost never have any kind of suspension since the weight penalty and pedaling energy they absorb would outweigh any benefit on pavement. Between the riding posture, comparatively harsh ride, and typically firm saddles, casual recreational riders may find road bikes to be uncomfortable. Hybrids won't generally be as light, which gives hybrids a pricing advantage since lighter components are generally more expensive. Hybrids are also aimed at more casual riders who won't necessarily want to ride fast enough or long enough for aerodynamics to be a big issue, so they'll have straight handlebars for a more upright riding posture. Hybrids will also generally have wider tires and maybe a light duty suspension fork for some offroad or gravel trail use. And they'll typically come with a wider/softer saddle to be comfortable without needing padded shorts.