I would disagree with a lot that has been said about Strata in this thread. Much of it seems like it is coming from the uninformed or is biased. I think Strata is very competitively priced for its feature set. It has a lot going for it. For example
http://www.stratauniversity.com is an EXCELLENT resource for new and veteran users of the application and is constantly updated. And cheap! Please point me to something similar for Cheetah? And the community is active in posting new images to the gallery at
http://www.stratacafe.com as well as active in helping out new and existing users. The rendering engine is extremely quick, powerful and has an amazing tone to its output. And the control in the rendering engine far surpasses Cheetah on so many levels.
The modeling tools are extremely flexible and things like shapes (a form of instancing) are just wonderful. You can jump into an instance in a scene and edit it individually within its own coordinate system and then jump back into the scene and the changes propagate to all copies. And it has a full complement of SDS modeling tools as well as a very friendly bezier modeling toolset. Many of the tools are more easily understood compared to Cheetah's tools that often don't even use common naming standards. And people here complain about booleans in Cheetah? Well Strata has two amazing methods of boolean operations. Actual booleans that work very well and accurately resulting in clean meshes and a render time boolean operation know as antimatter.
Regarding the interface. I'd disagree that it is dated they updated (modernized it) the interface in the most recent release. And the development has been very steady so I wouldn't agree with that either. They are open to the community and listen to what the users want just as Martin does here. And I know that the next version is aimed towards improving the animation side of things.
I'd say once you learn Strata you'll find it much more capable in many ways than Cheetah on many levels. All of that in mind I'd say that Cheetah does have it's own benefits as well. It's much more cost effective! The node render system is interesting, but it's not as intuitive at first as Strata's layer based approach. I do like how Strata can literally layer materials on top of each other something that Cheetah can not do. Cheetah does have a better animation system. In my mind it all comes down to what you want to do, if you want to do illustration go with Strata as I'll admit that is where it excels, if you want to dabble and do a variety of things go with Cheetah. Cheetah is an excellent app for its price and I would say its definitely the more cost effective solution.