I officially have perfected buttercream.

Now for whipped icing.

I've seen a recipe for heavy whipping cream, sugar, and pudding mix. I'm wondering if it holds and has decent flavor.

Another recipe thats heavy whipping cream, sugar, and piping gel.. which in all honesty I'm not wanting to get into the weird ingredients like piping gel, gelatin, cornstarch, etc.

And lastly, Wiltons Whipped Icing. That I have tried twice, but it has no flavor and I'm afraid if I add extract it will make it watery (since its already runny.)

My goal is a whipped icing that I can make varieties of flavors with, and can be piped on a cupcake.

Whipping Cream and a box of instant pudding makes an easy (and tasty) mousse filling (no sugar needed).  I use it for filling, not piping, but I think it would hold up fine. It gets rather thick and you can adjust the amount of cream - little less, thicker; little more, thinner.  I stay on the thick side, since I use it to fill.