For retro games, your 030 is perfect. For graphic design, you may want something a bit faster. If you're going to be running 2D graphics software then an 030 will be ok, but an 060 would be much faster. If it's 3D graphics you'll be doing, then you will definitely want an 060 to increase rendering times.
The AmigaOne isn't available, and may never be again. If you want to replace your A1200 with a new Amiga-like computer, Pegasos or a PC with WinUAE are your only options at the moment.
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moto