An “all around alternative”? Nero has expanded its capabilities so much, there really aren’t too many media suites that offer all the same options. Roxio and Ashampoo are two options, but virtually no one I know uses either of them.
Which is why most of us use free software that is designed for specific tasks. ImgBurn is what we use for the actual burns to discs. It is possible to make audio cds in it by creating a cue file, and burning that. Very simple, but may not fit your needs exactly…
For creation of mp4 or mkv files, many are using Handbrake or VidCoder. MPC-HC or VLC instead of Nero Media Player, AVStoDVD for creation of DVD-video, etc. The free tools don’t come in one convenient package, but virtually all of them produce better output.
So what, exactly, do you work with in Nero, and what kinds of output are you looking for?