It's been a while since I reviewed the PIM world , but a post on CardDav sync between MacOS Mountain Lion (10.8) and Google Contacts brought me up to speed. In particular, I thought about the special case of a pre-Lion Mac user (Snow Leopard and Leopard especially - 10.6 and 10.5). I'll assume for the purposes of this post that every Mac users also has an iOS device.
Every Mac/iOS user has to choose between Google and Apple for Calendar and Contacts (and thus Email). On Mountain Lion (or Lion) the choice is more difficult; those operating systems can work directly with Apple's iCloud. So it's not a slam dunk decision .
On pre-Lion Macs however, the choice is fairly easy. Older Macs can't use iCloud sync or data services at all; they can only access the web interface to iCloud Contacts and Calendars. On the other hand, even old Mail.app can use Google's (troublesome) IMAP services, and old versions of iCal can more or less interoperate with Google Calendar. Google's web interface to Contacts is crude, but their Calendar web services are much more robust than iCloud calendar. If there were any doubt, Gmail and Google Docs would seal the deal .
So, if you're an iOS/Snow Leopard user you can (mercifully) forget about iCloud. You need to use Google; for maximal Google compatibility SL users can even install Chrome .
You still have one choice though. You can:
- pay for Google Apps ($50/year) and use ActiveSync  on your iPhone and web UI on your Mac with optional user of iCal (CalDAV) and Mail (IMAP) on the desktop 
- use ad-supported Google Services and use web UI on Mac and the standard sync services for iPhone or Mac: CalDAV (calendar), IMAP (Mail), CardDAV (iPhone, not Desktop alas).
I don't think ActiveSync is necessarily superior to CalDAV/IMAP/CardDAV any longer -- but it is simpler to setup on the iPhone. Still, that's not enough to choose between paid and ad-supported. The main thing you get for your $50/year is freedom from ads and phone support. The last isn't a small thing.
Snow Leopard users used to feel abandoned and left out. No longer! Sometimes lack of choice is a feature. Apple has spurned you, Google awaits with open arms. What are you waiting for?
 PIM: Personal Information Management. Always includes Calendar and Contacts; since PalmOS usually tasks and notes (or equivalents). In the 90s it was mostly PalmOS and Palm Desktop for me, in 2013 it's a bit more complex:
- Contacts: iOS/iCloud/MacOS/Win7OutlookExchange via ActiveSync + Google/MacOS via CardDAV
- Tasks: Todo.app/Toodledo via proprietary + iOS/Win7OutlookExchange via ActiveSync
- Notes; Simplenote/Notational Velocity
- Calendar: iOS/Google via ActiveSync + iOS/Win7OutlookExchange via ActiveSync
I've simplified a few of those connections. I think we're starting to hit the boundaries of human cognition.
 If you're Mac/Android you have to Go Google. Mac/RIM or Mac/Microsoft -- you're on your own and you're used to being hard core.
 I've largely gone Google myself.
 I don't think Google offers free versions of Google Apps any longer. I'm from the early generation when it wasn't hard to end up with a half-dozen App/Domain combinations all of which were grandfathered in to ActiveSync support.
 Real old Mac users may want to try Camino.
 It's not clear to me that Google Apps users can use CardDAV services.
 iCloud can still be used for iDevice backup and media services, but trusted friends tell me the backup is unreliable.