Hi Marianna,
In my experience people find a DSLR brand they like and then stick to it. That has definitely been the case with me and Nikon. I really like the cameras they make and now that I have some nice lenses I'm very unlikely to move to another brand. That also means (1) I'm biased and (2) I know very little about the other brands.
Nikon cameras tend to be a little heavier and bigger than the others (Canon, for example). But they are built fantastically well. In general it is important to hold the camera in your hand and think twice about getting it if it is way too heavy or awkward. A little heavy or a little awkward is fine -- you'll get used to it over time.
You said lower end of the price spectrum, but I'm not sure exactly what that means. Nikon has a D3000 for about $450 and a D5000 for about $650 (on Amazon right now). I think both would be fine cameras, but the main differences appear to be that the D5000...
- has a better sensor (the same one that is in my D90)
- can do movies and
- has "Live View" (the mode where you watch the LCD instead of holding your eye to the viewfinder)
In my opinion these three things add a lot of value, but if $500 is your upper limit, then the D3000 is a very good option too.
BTW, from a picture quality perspective the lens can be more important than the camera itself. These two cameras often sell in a kit with a 18-55mm lens that is a decent start, but you might want to add lenses later, like a longer zoom or a fast lens for indoor shooting without the flash.
And in case you're not familiar with the lens specs, "18mm-55mm" means it can zoom and specifies the range. At the "18mm" end you get a very wide angle shot (e.g. for a landscape), and at "55mm" it is more zoomed in (e.g. for a portrait).
I avoid lenses that try to do everything, like the ones that zoom all the way from 18 to 200, or even 300, because they generally do this at the price of image quality.
A lens like the Nikon “35mm f/1.8G” is expensive ($200 or so), but opens up so many possibilities. That “1.8” (lower is better) means it is a fast lens and therefore can take pictures in low light. It is fixed focus though, so no zooming. I have a 1.4G that was very expensive, but changed my life. But these lenses are things that you can add later regardless of the camera you buy now.
I hope this helps. Don't hesitate to ask if you have more questions!
