My first dies were the oval and circle nestabilites and the oval and circle scallop nestabilites (spellbinders) and I progressed from there. They are really expensive over here so I only pick what I'll use often, I have quite a few now. I started with christmas embossing folders those were Cuttle bug ones.
Does brand make a difference, I personally don't think so, as I've since picked up some really great cheap dies and embossing folders. Others may have a different view??
It comes down to how much you're prepared to spend on your hobby