Thanks to iCloud, syncing an iPhone with a Mac is a piece of cake. But Mac users who don't buy into the whole "one vendor to rule them all" thing will find that syncing an Android phone with OS X isn't quite as easy. That said, it isn't terribly difficult, either, thanks to Google's own cloud services.
First, you must set up your phone to sync with your Google account. To make sure that this syncing is enabled, go to Settings > Accounts > Google, and tap your email address (it will be at the top of the screen, under the Accounts heading). Then confirm that the Sync Contacts box is checked.
Next, open the Address Book app on your Mac, go to Address Book > Preferences > Accounts, and choose On My Mac. You'll see two boxes: one that says 'Synchronize to Yahoo' and another that says 'Synchronize to Google'. Check the Synchronize to Google box, press Accept in the pop-up box, and enter your Gmail address and password when prompted. You should now see a small sync symbol in your Mac's menubar. Click this symbol, and choose Sync Now from the dropdown menu.
To sync your Android/Google calendar with iCal, open the iCal app on your Mac and navigate to iCal > Preferences > Accounts. Click the plus (+) symbol in the lower left corner to add a calendar to iCal. Leave 'Account Type' set to Automatic, fill in your Gmail address and password, and click Create.
If you have multiple Google calendars associated with your account, you can choose which ones to show in iCal by clicking Delegation (iCal > Preferences > Accounts), and checking (or unchecking) the appropriate boxes.
One of the easiest ways to sync media, including music, videos, photos, and podcasts, is to use DoubleTwist--a free Android app that's commonly known as "iTunes for Android." You can sync media with DoubleTwist either via a USB cable (which is free) or via Wi-Fi (which requires a one-time $5 download of AirSync by DoubleTwist).
Regular USB syncing over DoubleTwist works with Android devices that have USB mass storage (MSC) mode enabled. Android devices running Jelly Bean or later support USB MTP mode but not USB MSC mode. Consequently, until DoubleTwist updates its app to support USB MTP, these devices (which include the Samsung Galaxy S3 and the Samsung Galaxy Note 2) can sync only over Wi-Fi via AirSync.
To get started with DoubleTwist, download and install the free DoubleTwist desktop app on your Mac. When you open the program for the first time, it will scan your iTunes and import your media (music, videos, photos, and podcasts). It won't automatically import your playlists, but you can manually import them: Go to Playlist Setup (in the lower left menu), and select Import iTunes Playlists. If you want DoubleTwist to automatically import changes made to your playlists in the future, check the box next to Automatically Import iTunes Playlist Changes.
Next, download the free DoubleTwist app to your Android phone. Then use a USB cable to connect your phone to your Mac, and follow the instructions on the screen to mount your phone to your computer. Once your phone is mounted, click on your device (in the lower left menu) to open the sync options. You can sync all of your music and videos at once, or you can pick and choose different playlists to sync. You can also drag and drop files and photos to your device.
Syncing nonmedia files, such as documents and spreadsheets, between your Android phone and your Mac is easy, thanks to cloud storage services. In this example we'll use Dropbox (and assume that you already have it set up on your Mac), but you can use any service that appeals to you, such as Box, Google Drive, SkyDrive, or SugarSync.
Download the Dropbox app on your Android phone. From there, sign in to Dropbox with your account info. Thereafter, any file you place in your Dropbox folder will be synced between your devices automatically.
As on the iPhone, you can choose to have Dropbox automatically save and sync the pictures you take on your Android phone (you get an extra 500MB of storage space if you enable this option). This option is similar to Google's option to automatically upload photos taken to your Google account, and it can be a little creepy at first (maybe you don't want those photos to be synced off your phone), but it can be useful if you lose your device.
The easiest way to sync everything from your Android device to your Mac is to use Google's own apps for email, calendaring, photos, and contacts. If you do, you can enable syncing from your Web-based Google account to your Android device by going to Settings > Accounts > Google and tapping your Google account (under Accounts).
From this menu, you can toggle syncing of various Google services--including Google Chrome, Photos, Google Play Books, Google Play Magazines, Google Play Music, Google+, and Picasa Web albums--on or off. You can also choose to sync the Internet, an interesting feature that syncs your Google search results across devices.