All programs' audio engines have slightly different characteristics for summing, panning, etc. However, the impact of the software on your sound is minimal compared to your source instruments, room, mics, preamps, converters, cables, etc. I've never heard someone say "that sounds like Sonar" or "that sounds like ProTools." What I'm saying is, it would take some stellar ears to be able to hear the very subtle differences between software programs. Just pick one and start learning to use it. Focus on everything else in your signal chain first, before worrying about how the software will affect your sound.