As a Gentoo Linux user/lover for years, I must disagree.
Unix-like systems are NOT suited for the desktop. They are big, obscure, clumsy and hard to work with (and I mean OS-level work, not internet web-browsing or office productivity). You can, to a certain degree, get used to them and build a fast, somewhat light system taking Linux sources as a base (the Gentoo way is just an example), but it's NOT amiga-ish at all: it's just the opposite: the Amiga was conceived to be a desktop system, friendly and accessible right from the start.
However, with the advent of wayland-based distros, we *could* hope for faster, lighter Linux systems. But nowadays, any Linux distro (unles you build from sources and adapt it to your hardware/software requeriments), Unix-like is NOT amiga at all.
Closest hardware to Amiga is the Minimig (call it V1-1 original Minimig, FPGA arcade, Altera DE1 with the awesome chaos work or even Chameleon 64 core port): it IS amiga hardware capable of running true legacy Amiga software.
AROS is AmigaOS done right: open-sourced reimplementation. If you want an Amiga OS for non-commodore or FPGA hardware (I must insist you consider the second option if you want legacy software running perfect), then look no further: AROS is what you want.
Other OSes similar to the Amiga OS idea of accesibility and great response with a reasonable hard/soft integration are, imho, Risc OS (get your Risc OS computer for a low price, as it's compatible with the Beagleboard, Pandaboard and Raspberry Pi- yes it runs already on the Pi!), and Haiku (BeOS).
