What's the best SoundFont editor/creator?

I've used Polyphone for a while now. It's been getting a lot more stable and user friendly as time goes on. I really like it. It works to make sf2 files of all varieties including GM banks.

http://polyphone-soundfonts.com/en/

As StringContrabass says there is Polyphone, but I suspect you will find it just as confusing as Viena.

In order to make a soundfont you have to understand the principles of sound synthesis, and a fair bit about how the physics of a soundwave work. You will also need to be familiar with recording techniques.

As a rule soundfont creation software does not include the facility for recording samples, but expects the samples to have been recorded beforehand. You then use the soundfont editor to compile the samples into a soundfont.

There is a wealth of material to be found via Google on this subject, but a good starting point may be this article from the University of Salford's website......
http://www.acoustics.salford.ac.uk/acoustics_info/sound_synthesis/

HTH

I must recommend Polyphone Soundfont Editor, Which I'm used to make my ColomboGMGS2 soundfont.
You can simply set the information on your creation. When you create a new project, The home view contains 4 tabs, Samples, Instruments and Presets. So easy to set any kinds of parameters, key or velocity ranges and loops precisely.
Also It's so simple to import or record *.wav samples By the top panel buttons...

I Do Not Know How To Use Polyphone