Canon and Nikon are obviously the most popular, especially around the serious professionals. But a professional full frame sensor DSLR camera is outside your budget and probably more camera than you need (as a beginner). Buying an expensive camera does not make you a better photographer, just as buying an expensive hair brush or makeup kit doesn't make you a better makeup artist. The art comes from the person, not the tool.
When choosing the right tool for your trade, you need to make sure the tool fits your hand and is comfortable for you to use. The grip on cameras do vary considerably between models and manufacturers. Sony recently changed some of the technology in the DSLR cameras, which reduced the moving parts and changed the weight (feel) of the camera. I know a few people who feel more comfortable with the fit and feel of a Sony, rather than the Canon and Nikon. But I've also heard people complain about the feel of the Sony, so it truly is a personal choice based on many factors. That is why I strongly recommend that you visit a camera store and hold each camera for several minutes to get a good feel for it. Try taking pictures with the cameras in different positions, angles and orientations...similar to what you would do in real life. For example, hold the camera in portrait orientation versus landscape, paying attention to how comfortable it fits your hands, face and eye. Take note of how easy it is to adjust the dials, press the buttons and navigate the camera features. People who are paying for your services, don't want to wait while you spend a huge amount of time trying to change a camera setting...so get a feel in the store on how fast you can adjust the settings.
The camera body is an important piece of equipment, but if you are seriously looking into making money as a photographer then you need other photography tools. Lighting and tools to control lighting are important. You don't want to rely on the pop-up flash for a professional picture. Hot-shoe flash, umbrella lighting, reflectors and soft boxes are just some of the other tools you may need to consider. A good tripod or monopod is often important for steadying the camera. Picture editing software is very important in producing a finished image rather than a raw photo. Some other items to consider are extra lenses, cleaning tools, filters, reflectors, white balance cards, back drops and a camera bag to store your equipment. When you add up the cost of these other items, they can be as much or more than the camera body. I could easily argue that some of these extra items are just as important as the camera. For example, poor lighting can ruin a picture, but most point-&-shoot cameras can take a good picture if it has good lighting (not that I'm advocating for a point-&-shoot).
To be honest, a $1500 budget is not much to start with, if that is your total budget for all your photography gear. A good camera bag to protect your investment will cost between $50 and $100. Good photo editing software will cost roughly between $100 - $600. A good flash or portable lighting will start around $200. You may need an extra battery, cleaning tools and other small items that would easily add up to $100. That leaves about $1000 or less for your camera body and lenses.