I agree with END.
It also depends on your space.
I've got a small apartment and no room for a desk and huge computer. Hence, staying with my laptop. This laptop was also practical and useful in college when I needed its small footprint and mobility.
The power and upgrade ability of desktops is an obvious plus, so if you have the space and don't need to be mobile, then go for that. It's also the cheaper route. However, for animating and most editing, the power of even a decent laptop will be fine.
It's almost like the webcam/DSLR argument. A webcam, like a laptop, can work perfectly fine for animation. However, a DSLR, like the desktop, has much more power and adaptability for stuff outside of brickfilming. I'd rarely recommend somebody buy a DSLR just for brickfilming, just like somebody doesn't need to build a gaming computer just for brickfilming.
So check out your other needs, as well as your space and budget.
However, from your question, it sounds like you might already have a laptop. If there's no pressing reason to replace it now, (constant crashes, getting obsolete, etc...) and it's working well, just stick with it for now and save up your money for later. If it ain't broke, don't fix it.