I was recently in a similar boat, and this forum has tons of great and helpful info! Oracal 651 seems so be a favorite amongst many, sounds very versatile and moderately durable. And it's very reasonably priced (most places), it's what I've been ordering lately.
If you decide to work with Oracal brand, one thing
I highly suggest you do is request a FREE color chart from their website:
ORACAL USA
Go to Products > All products list > scroll down to
ORACAL 651 Intermediate Cal and click > then click tab that says "Request Samples & Collateral".
Now it will require you to create log in information, but this chart is well worth it! And it's free, some sites offer to sell it for $10.00. You don't need to be a business, it can be for personal use. The chart they send out also includes color samples and info for all their vinyl, not just 651. Also request sample sheets of their different vinyl.