[Eru]

I personally use Razor since it's really easy and is all set up through the GUI. You can also use Injection, but you have to write your own macros using Injection's scripting language (or find the macros that someone else has written already.) The only *real* advantage that Injection has over Razor is that it apparently has a little less lag and interacts with the client faster. The downside is that it's harder to use, can only use specific clients (usually older), and is more prone to crashing if you don't know it very well (which is hard because there's next to no documentation).

TL;DR - I like Razor.