How does AACplus v2 perform in comparison to AAC?

Question

Which of these audio codecs provides better quality? I want to encode my audio files to lower lower bitrate and maximum quality.

Solution

HE-AAC v2 (the standardized name of what is "aacPlus v2" as a trade name) supersedes the AAC standard.

It has been extensively tested, and results suggest that it provides excellent quality even at 48 kBit/s (whereas MP3 only scored as "poor"). I can only recommend to look into this 2009 EBU Technical Review for a detailed description.

Here, you can see the subjective scores (higher is better) for various bitrates.

Another figure that shows how it results in better quality at lower bitrates:

To summarize:

Preliminary studies show that the compression efficiency of AAC can be increased by a factor of up to four. HE-AAC v2 – the combination of AAC, SBR and PS – is undoubtedly the most powerful audio codec available today. It is thus the first choice for all application scenarios where bandwidth is limited or very expensive, such as digital broadcasting or mobile applications

It should be noted though that if you want to use bitrates above 128 kBit/s, there is no point whatsoever in using HE-AAC, since you won't hear a difference.