There are dozens of different digital cameras available today. They all offer something slightly different from each other, which makes picking out any particular model as the best rather difficult.
If you're looking to buy a new camera, there's a variety of factors you should consider. It's easiest to split all these cameras up into a few distinct groups, choose your favourite, and then work from there.
A General Rule
With digital cameras, any brand and any camera type will always have a beginner-level, an intermediate and a serious enthusiast-level variant. As you go up in specifications, you don't always get more features, since entry-level cameras these days are pretty chock-full of extras.
What you do get is objectively better build quality, objectively better image quality, and subjectively better control layouts. All of these can be invaluable in taking better photos, but they might not be as crucial to you as saving a significant amount of money by buying a lesser model.
What Do You Need In A Camera?
To be entirely honest, there's no point buying a camera that doesn't fit your needs. If you want a camera you can stash in your purse or pocket, there's not much point blowing $5000 on a professional digital SLR.
Each camera has its own place in the digital imaging hierarchy, and sure, paying more should get you a theoretically better camera, but if you don't need most or all of the features you're paying extra for, don't bother. Photography is about taking photos, and you should be buying the camera that you find the most appropriate for that task.
More advanced cameras are also more demanding; it's all well and good to have a thick booklet full of user modes and manual settings, but if you do get a camera with these capabilities, learn them and take advantage of them - your photos will thank you for it.
'Crop' sensors are usually found in entry-level and intermediate digital SLRs. Like their name suggests, they're smaller than the full-frame sensors used in (most) pro-level DSLRs. This isn't necessarily a bad thing, since sensor technology has evolved in leaps and bounds, and several intermediate-level DSLRs can truly rival their full-frame counterparts for image quality.
Crop sensors appear in everything from the entry-level Canon EOS 100D, to the mid-range Nikon D5300, to the semi-professional Pentax K-3. You should consider a crop sensor digital SLR as your standard choice when choosing a camera; they're the format that has been around the longest, they offer great image quality in a moderately-sized package, and they have the widest selection of lenses available.
Full-frame sensors are serious business. Digital SLRs that have full-frame sensors are exclusively high-end, semi-professional and professional models. A full-frame sensor is the largest mass-produced digital camera sensor, and offers the outright best image quality, especially in low light.
Digital SLRs with full-frame sensors include the semi-pro Nikon D610, as well as professional models like the Canon EOS 5D Mark III and the Canon EOS 1D X. You should consider a full-frame digital SLR if you want the absolute best image quality, ergonomics and build quality available -- damn the weight, the size, and the expense.
Mirrorless (CSC) Cameras
The mirrorless camera category is still relatively new compared to the digital SLR, but it's growing quickly. There are nearly a dozen major mirrorless camera brands, all of which make models that are equally appealing for different reasons. They're available in a range of sizes and styles, but generally they're significantly smaller than digital SLRs, with similar or slightly smaller imaging sensors in most cases.
Mirrorless cameras go by any of a few different names. You might see them called compact system cameras (CSCs), mirrorless system cameras (MSCs), electronic viewfinder with interchangeable lens cameras (EVILs), or digital or mirrorless interchangeable lens cameras (MILCs). Basically, a mirrorless camera is one that doesn’t have a mirror or mirror box inside its body, reflecting light through the lens to an optical viewfinder (like the one on top of a digital SLR).
We give you a whole lot more information on mirrorless cameras in our buying guide. The mirrorless camera category includes models like the full-frame Sony Alpha A7R, the waterproof Nikon 1 AW1, the miniscule Panasonic DMC-GM1, and the DSLR-esque Olympus OM-D E-M1. Mirrorless cameras span a huge range of sizes, designs and mission statements; but if you don't like the look of a digital SLR, but want something more versatile than a point-and-shoot compact camera, a mirrorless shooter is the way to go.
Also known as point-and-shoot cameras, this class of camera is handily compact. With relatively small imaging sensors, they're mostly designed without viewfinders or extensive controls, simplifying the process of taking photos down to a few dials and buttons. They generally have collapsible, powered zoom lenses, which retract into the camera's body when it's switched off. Like mirrorless cameras, compacts can come in a range of sizes, but as a general rule they're the smallest cameras you can buy.
Buy a compact camera if you want to take it everywhere. Compact cameras are incredibly convenient - you can stash them in a purse or back pocket, and you'll always have them handy to catch that once-in-a-lifetime photo. They do sacrifice outright image quality and easy-to-handle controls, though, so you're trading crispness for convenience.
Compact cameras range from entry-level to enthusiast, and include the tiny but powerful Canon S120, and the more versatile Sony RX100 II. They're great little devices, and you'll be able to take pictures that you're proud of, but you can get better results with a mirrorless camera that's only slightly larger.