I've used both Sierra and Ninja and am happy with both. I use Ninja now because the broker picks up the fee; however at $25/month, Sierra charts are practically free anyway.

I guess I like them both for the same reasons: you can set them up anyway you like, with any bar pattern (except point 'n figure, but I understand Ninja's including that in their next upgrade which is already 2 months overdue), they both have an endless assortment of studies and indicators, and you can change anything about the chart you want (colours, backgrounds, displays, etc) to suit your eye.

The downside is that both have a bit of a learning curve to learn to use. Ninja has a good forum and webinar lessons to help, but mostly it's trial and error. If you like I can show you the Ninja stuff I know at one of the webinars to give you an idea as to how the charts work, how to set them up, etc.

If I had to choose between the two, I'd probably go with Ninja. I was reluctant to switch over at first, but I think that Ninja has the greater flexibility of the two. Sierra's great though, don't get me wrong, but if you made me choose, I'd take the Ninja.

That's my two cents,

Erich