I am a long time user of both programs. Aspire since it's initial introduction, Rhino for the last 5 years. Following are my opinions of these software programs.

Aspire is not 3D CAD by a long shot. Rhino definitely is 3D.
Organic modeling in Aspire can be tedious with slow regen times. Rhino is much more dynamic. Rhino has a "history" that allows tweaks to organic profiles to be made in virtually real time. That is huge when designing. Aspire's design tools are a bit on the strange side, a lot of them are quite different from what could be considered industry standard.

Very little has been done over the years to add tool pathing strategies in Vectric products. There are nowhere near the strategies that are available in various levels of RhinoCAM. More disturbing, there seems to be no plans to add strategies like pencil line machining and others. I would have thought at least a few would have appeared in the last 18 years I have been using the software. . .

Cost. As of this writing, Aspire is about $2000 US. Rhino CAD is about $1000 US. RhinoCAM Xpress $600 US, Standard $1500 US.

So, for about $500 more, you get real 3D CAD and much more capable CAM with Rhino. Xpress is a bit too limited in my opinion.

I started using Rhino because I added 3D printing to my capabilities. Aspire is extremely limited when it comes to designing true 3D items. Right off the bat, no overhangs are possible. Later on I added a laser machine. Turns out Aspire does not program that either. Can't even talk about LightBurn on their forum, it is banned.

Both of these programs have steep learning curves. In the end, it is worth the effort. Most of us have learned, "Easy to Use" translates to "Limited Ability". Well, Aspire is not easy to use, and it still has limited ability.

If you are thinking about expanding your capabilities beyond CNC routing, Aspire is definitely NOT the way to go.