There are two free ones I use:
AQTime from Smart Bear software (the free one lacks the cool integration in Visual Studio that shows the percentage of time spent for each line within a routine in the margin/gutter).
Download the free version here:
http://smartbear.com/products/free-tools/aqtime-standard/
Ocasionally I also use the free profiler that comes with SharpDevelop:
http://www.icsharpcode.net/opensource/sd/download/
I prefer the AQTime Pro though, it has a steeper learning curve but once you get the hang it really provides allot of insight (I use it for analyzing code, not for speed optimization but simply tracing the paths of code (who calls this method when I click on ...).
Tried the JetBrains once, but I found it was lacking too many features to spend anything on it.
Never tried the RedGate one yet.
Edit: There's another one I use for a quick glance of what's going on: SoftwareTrails (http://www.lovettsoftware.com/LovettSoftware/post/2012/09/07/Software-Trails.aspx). It's the simpelest to set up and built for real time analysis instead of viewing the results afterwards.
