Which no calorie artificial sweetener do you use?

I use Splenda (sucralose) and I avoid equal (aspartame) (and foods that contain it) and sweet n low (saccharin). Saccharin has a history of possibly being linked to cancer (not conclusive but the FDA still says it's a potential risk). Now that said, all of the major artificial sweeteners may be hazardous, I am just careful in light of this to use it very sparingly and eat whole foods whenever possible...I just use a packet or two for my iced coffee.

CNN article from a few weeks ago: http://www.cnn.com/2013/07/15/health/artificial-sweeteners-s oda

truvia

Splenda!

Splenda 

I use Splenda in baking but I use less. It seems so super sweet to me. In beverages, I like stevia. 

Splenda!!!

Stevia. I choose the Sweetleaf brand of Stevia as it's the only one that isn't chemically processed during the extraction process.  
I use drops for liquids and powder for baking. Some brands have a bitter aftertaste. I've heard good things about KAL brand from amazon but haven't researched it yet to determine additional ingredients. 

Splenda is poison as is aspartame. 

Splenda Addict here!

I use pure stevia - you have to be careful as most of the brands of stevia still contain the other sweeteners in them as well.  The ingredients should just say stevia.  SweetLeaf is a good brand and tastes great.