I went thru this exercise myself a couple of years back.  Even kicked off a
thread on a Mac email list.
I don't/didn't have any experience or background with the Mac on the 68K, so
that didn't come into my decision making.
I ultimately decided that I didn't need the fastest/biggest/most memory power
house Mac that would run Classic.  I just needed to run my Mac OS apps and games
that would never be ported to x86.
I purchased a G4 cube and have been happy with that decision.  I can boot up
into Mac OS 9.x, and also boot into OS X 10.4 with Classic support.
This was what worked well for me.  I will be interested to see what you
ultimately end up choosing.
Jerry
On 07/15/16 02:03 PM, Austin Pass wrote:
  I'm toying with putting the "ultimate"
classic Mac together, although I'm
 having a little difficulty pinning down the definition of what the ultimate
 representation of the type is, so was looking for a little input from
 Classic CMP'ers.
 I'm aware that there's a clear divide between Motorola and PowerPC CPU'd
 variants, so I'm going to plump for a PowerPC based version so that I can
 get access to newer hardware and use it as a kind of bridge system between
 my current computers and the more historic versions.
 In terms of hardware I have a lovely mirror-door G4 PowerMac I'm intending
 to use.  I have the original media that shipped with this, so I can get
 9.2.1 on it relatively easily.  Are there any add-in cards (PCI) I should
 be considering?  It has a built in Airport Card (possibly Airport Extreme?)
 although my home Wi-Fi is 802.11n or better with WPA2 so I'll just use
 Ethernet to connect it to my LAN.  Was a gigabit ethernet card ever
 released with Mac OS 9 drivers?  I have a couple of 600GB PATA disks that I
 can use with it, but has there ever been a SATA implementation that worked
 with classic Mac OS?
 Also, I have an Asant? ether bridge tucked away somewhere that I hope to be
 able to use to connect some of my older Mac OS boxen without Ethernet.
 In terms of the software - any top-line utilities or System Extensions I
 should look to get my hands on?  What's the state of the art in classic Mac
 OS browsing nowadays, Mr Kaiser - is Clasilla still maintained?
 -Austin.