I'm sorry, but you opened yourself up for this one... Any software that can decode FLAC to WAV will do exactly the same job as far sound quality is concerned. There will be no "better". FLAC to WAV conversion is very well defined - there's no room for improvement and since most tools rely on a standard library to encode/decode, there's little chance that many of them will screw it up, either. As far as the user interface is concerned, "better" is subjective, but some will be easier to use and some more flexible than others.
(I assume you're looking for Windows software. If not, there are comparable programs for the Mac.)
If preserving tagging is of no concern, you can use the
FLAC Frontend tool installed with the
FLAC software package that is downloaded from the FLAC site at SourceForge.
A better tool may be
dbpoweramp Music Converter. I think it will transfer any tagging to an ID3v2 tag in the WAV file. The illustrate/dbpoweramp web site is a confusing mess. There's a paid version of dbpoweramp, but you don't need it to do format conversions. Download the free/trial version (the "Install" button at the link above), which won't expire and will give you all the capabilities you need.
Another good tool is
foobar2000, which is both a player and a music library manager that is highly customizable and can perform a thousand different tasks. Many people find the interface to be
too customizable and the program to be
too all-inclusive, but if Swiss Army knives are your preference, it's a good option.