I have two sets of Denise needles, and love them. I also have a set of Boye interchangeables, and use them if the pattern calls for a needle size which is not part of my Denise sets. I prefer the Denise needles, though, because I have arthritis, and the Denise needles are very easy for me to put together.
I also use plenty of straights and dpns and fixed circular needles. I have all kinds, and usually try about 3 or 4 different kinds with each new yarn I work with. Yarns are so varied, and they require different kinds of needles when knitting with them.
So, I think you should just enjoy buying all the needles you want!