I use Wavepad, simple GUI, free and small. Oh, and fast! Very fast. 
I use Adobe Audition 1.5 (CoolEdit) for years now. To be able to use your vst’s as effect processing is so sweet!
I just love Adobe Audition.
It kinda reminds me of Renoise. It’s easy on top, and has lots of small hidden useful features that can really speed things up. 
Is there a way of Renoise to open an external wav editor and when you close it the altered sample is in Renoise? No? Can we make it so?
In fact, I did ask this very same thing about a year ago.
would be very nice to have this.
yea, i use audacity too, though I don’t really like it.
I use the shareware version of cooledit 96 for some of the stranger, heavier lifting.
audition. I stick with this program since cooledit 96, it simply feels right for me. (never got used to soundforge …).
to answer to the question: wavelab
I use wavelab also.
but for multi-track recording I use Kristal audio engine:
audition
wavelab.
mlon
ReZound
I find a combination of Audiacity (for a whole project, as it’s a multitrack editor) and Wavepad (for the single files) works like a charm.
wavelab5, feels most convenient for me.
Just Good 'ole Goldwave here.
Samplitude 8.01
But there are some good multitrackers out there nearly for free:
Check
Kristal
http://www.kreatives.org/kristal/index.php
Or use audacity. The only one Ii know which runs in win as well as in linux as well as in OsX
http://audacity.sourceforge.net/
or try
Ntrax
http://www.fasoft.com/what_is.shtm
Not for free but cheap.
Prehaps you might want to add
for some issues.
Sony Sound Forge 7.0
Cool Edit Pro 1.2 (v2 is slower than a dea turtle in the desert plus they ruined the ergonomy)…