Which is the best mp3 editing tool

I have a number of audio files that is going to be used for a project work. The most simplest way to work with audio file is to convert them in mp3 and then move them. Because it is a very common format. I want to know that which is the best mp3 editor. Why I want to know this because the audio file long and short. I have to edit them merge them and then create a new single file. So I need some suggestion on a beset mp3 editor which is easy as well as multi functional also. For example I can see the bitrate chart, equalizer effect, audio restoration, etc. Thanks in advance.

There are tons of tool on the internet available for free download. But as you mentioned that you need to have a bitrate chart then this can work for your. The tool is called Wave MP3 Editor. The link below is a evaluation version. But if you like you can upgrade to full by buying it. As per my view this tool is suitable for both a beginner and pro. Supports many audio formats and has many extra tools. Download it and try it.
Wave MP3 Editor.

I am quiet familiar with WavePad Editor. A freeware professional audio editing software. The software interface allows you to just cut, copy and paste option. This are easiest I ever show. Add multiple audio files by copy pasting and create a new one. The simple options like cut, copy, paste, delete, insert, silence, etc are included in it by one click. As you need it is equipped with audio effects which comprises of amplifier, equalizer, echo, revers, etc. At one time you can work on multiple audios. A speech tool is added in this software to analysis on air speech recording.
Download WavePad Audio Editing Software

If you have Nero in your system then you can use a audio editor tool in that. Nero utilities has a wave editor. Very powerful and flexible tool. I think it is called as Nero MP3 Pro. The software supports a powerful editing for mp3 audios. The best thing about the software is that whatever you do split a audio or merge it will preserve the quality of the audio file. The quality does not degrades in this.