By the wording of your question, it sounds like you're someone who is interested in photography, and wants to upgrade from maybe a point-and-shoot camera to a more advanced one like a DSLR.
If so, the best DSLRs will vary depending what your needs are and your budget.
For the entry-level crowd: The Pentax K series offers the best ISO performance, control, capabilities, and the best overall user experience. No DSLR currently on the market is a bad one, so if you can not take a good picture with one, it's not the camera's fault.
You mentioned iso, exposure and shutter speed changes. These are standard features/controls found on all DSLRs and mirrorless cameras too. What will separate one camera from another is how fast it focuses, how fast it can continuously shoot and for how long, which is to say how many shoots in continuous shooting mode can the camera take at the highest fps before the internal buffer fills up and the camera bogs down to just 1 fps.
Some other features that most people find extremely useful is image stabilization. Canon and Nikon puts their stabilization systems in their lenses. The downside to this is that not all lenses have IS, especially cheap kit lens and even most expensive primes. Pentax has the advantage here with their in-body image stabilization (IBIS). Since the sensor is moving to control camera shake, you can now use any lens and have the image stabilized. Even old lenses from the film days, it's doesn't matter. IBIS will allow you to shoot 3-5 stops lower ISO or slower shutter speed for razor-sharp images, often with zero grain.
The Pentax shoot at a faster frame rate, and has a faster shutter speed compared to comparable bodies from Canon or Nikon. In the entry and mid-level range of DSLRs, Pentax is the only one to have a seal body to make it weather and dust proof. You could hose down their DSLR and WR lenses without any problems.
You don't state a budget or what types of photos you like to take. Again, I'm guessing based on your question that you're just starting out, so it is too much to recommend a higher-end camera like a Pentax K-3 II, Nikon D7xxx series, or a Canon 70D or 80D. You would be better off getting a cheaper body with better lenses since it's the lens that determines sharpness. Of course, if you can afford a higher-end camera like a K-3 II, D7200, or a 80D, then go for it. The higher-end bodies have more capabilities and performance that will allow you to consistently get acceptable results of a broader range of subject matter in a larger variety of shooting situations. Getting a mid-level body now means that you'll more than likely not outgrow the camera for several years or more. However, do not fall for the trap that a better camera equals better image quality. Even if you shot a Nikon D5 along with a D3200, at the end of the day you would not take any better or worse shots with either camera.