Your "Google Contacts" can technically include anyone you've ever emailed. I wouldn't want all those people on my phone. Personally, I like the Verizon Backup Assistant. It's a simple and easy way for me to transfer my important contacts from one phone to another.
Edit: It also includes people you're following on Google+ now. I follow a lot of people I don't necessarily need in my contacts. I know a lot of people will disagree, but I really do like Verizon's Backup Assistant.
I have stored all my backups on my Google account for quite some time. None of my contacts are random people I have emailed. Gmail stores those contacts as "Other Contacts" by default. They will be autofilled when trying to email them again (Which is nice) but they do no clutter my contacts on my phone.
Very easy and convenient because my contacts are always saved, and constantly updated as I update them on my phone.