Unfortunately, since 2005 these three emulators aren't really actively developed on. From time to time, another patch appears, but the future doesn't look so bright - new features are rare. This doesn't mean the emulators are unusable today, but don't expect them to run under Vista or MacOS 10.5. I had no problem with them on Windows XP, SuSE 10.1 or MacOS 10.3.9, but these operating systems aren't state-of-the-art anymore.
It is wonderfully stable but a little bit long in the tooth. Today a G4 is still considered a fast processor and each instruction has to be simulated on a x86 processor. This can be a 100 times slower in the worst case. But PearPC does have a JIT-compiler (just-in-time) to convert PPC instructions on demand into an immediate code, which can be run much faster.
Despite this i think the mediocre speed is the worst drawback of PearPC - much worse than the missing sound support.
And the best: Sound is working! A lot of old games run fine and i had a lot of fun!
But to operate this emulator, some preparation is necessary. First of all you need an old Mac - at least the ROM. A ROM (read only memory) contains the first program which the computer runs - on PC this is called BIOS. You can extract the contents of the ROM from an old Mac or you can try to find it on the internet. Good luck! Of course, Apple Inc. is eager to inhibit this.
Basilisk can emulate a bunch of different 32 bit Macs (from SE/30 to the Quadra) and operates with System 6, System 7 and MacOS 7.5 to 8.1.
But Basilisk is not as stable as PearPC - i have experienced crashes occasionally. But honest: In the old days we saw Error 11 often enough (even several times a day) or worse (mouse hangs). So i think this is less Basilisks but either MacOS or the applications fault.
What i didn't resolve is how to make native AppleTalk work. To do this, the emulator needs hefty support from the host operating system. What DID work is TCP/IP. And this gave me the chance to make at least AppleShare IP happen. See my comments at the end of this article.
SheepShaver supports all PCI PowerPC Macs from the 7200/75 up to the G4 but without MMU. All operating systems from MacOS 7.5.2 to 9.0.4 run un SheppShaver. Since MacOS 9.1, Apple requires a MMU.
For MacOS 7.5.2 to 8.1 one needs a so called "old world" ROM from a PowerMac 7200, 7500, 8500 or 9500. But if you plan to use MacOS 8.5 or newer, you have another option: "new world" ROMs are in reality EEPROMs and Apple distributes software updates for them. So look for the "iMac ROM Update" to gain a working ROM image.
But this leaves another difficulty: All MacOSes since 7.6.1 are not freely available. Now you can find the ROM, but have to buy the MacOS.
Ok, this is a job for e-bay.
For me, MacOS 7.5.5 has a very nostalgic character. I used and supported it for a long time when i was working for the Pirmasenser Zeitung, a local newspaper in Germany. My way started from MacOS 7.5.1 (which is nearly identical on 68k and PPC), over 7.5.2 (support for PCI slots) to 7.5.3 (via 7.5 update 2.0) and 7.5.5. And here we stayed a while - never change a running system!
So when i discovered the difficulties to emulate AppleTalk (which is a proprietary ethernet protocol), i remembered a trick to make at least AppleShare (the file sharing protocol from Apple) happen. In MacOS 8.0 and later, Apple introduced support for AppleShare over TCP/IP instead of AppleTalk. And at the Pirmasenser Zeitung, we had found a way to implant this into 7.5.5 too (a thousand thanks to Thomas).
Here is my receipe: Take OpenTransport 1.3.1 and patch it so it installs under 7.5.5 (it argues, it won't work below 7.6.1, but this is nonsense) and then put the extension AppleShare version 3.8.1 (from 8.0 or 8.1 i think) into the system folder.
One question remains and that is, where to find this! Maybe it can be found inside the updates that Apple provides! OT-1.3 can be found inside the MacOS 8.1 Update. The Update from 1.3 to 1.3.1 is downloadable too. And with Tomeviewer it is possible to extract files from a tome (which is the archive format for Apple installers) - for example the AppleShare extension.
But how this works exactly i still have to figure out yet.