Audio CD burning only
Burrrn:
Can create audio CD's from already compressed audio files like .mp3, .ogg, and some formats you may have never heard about, even uncompressed .wav. I highly recommend Burrrn. You won't find any easier way to quickly burrrn an audio CD, and you won't have to go through any options/settings to do so since it's all on the easy-to-use main GUI window. Whatsmore Burrrn automatically creates gapless audio CD's without 2 second gaps which is extremely useful because you'll never forget to enable such an option. Note: Burrrn only creates audio CD's!
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Data CD burning/and audio CD burning
Burnatonce:
Can do data, however you'll need to download ProDVD do burn DVD's with it. It can also do audio CD's like Burrrn however there's more steps in the creation of an audio CD using Burnatonce, and you have to manually enable the option to create gapless audio CD's without 2 second gaps.
DeepBurner Free:
The audio CD's it creates won't be gapless even if enabling the option for your burner drive, I tested it's ability to create a gapless CD and it doesn't work it will instead place 1.70 second gaps inbetween the tracks instead of the standard 2 second gaps. With that being said it could have been something to do with my system and the writer drive I used. It's ability to create data CD's is however very good, and it's what I use on my old Win98 system to create backup CD-RW's with.
CDBurnerXP Pro:
I found it to be a bit bloated when compared to Burnatonce and DeepBurner, however so as to not sound bias I'll let someone who actually uses it commit on it.