I second Mr. Overflow and would go for an Amiga 1200 with the Vampire II when its ready for the system. It will be a super-fast classic setup with thousands upon thousands of utilities, games, music and other stuff to explore.
Amiga only? It does depend on what one use a computer for. My impression is that many people use their systems for accessing Internet to use social media, browse sites, not so much other tasks. If you have a tablet (iPad, Android), this could be a good substitute for this. You can do most general Internet stuff on those things like banking, shopping, Facebook, Twitter etc. Then you can use your Amiga for creative computer stuff.
I actually feel more creative when in front of an Amiga, be it classic or the AmigaOS 4.1 variant. I'm most creative without access to the Internet, because the "net" tends to steal my focus and energy and drive me to various forums, eBay, news and vids on YouTube.
When I'm on the PC it is even worse, because there I got Steam lurking in the background!
