Litmus is beneficial to determine whether something is acidic or alkaline because it's easy to get a read. Red-blue or blue-red its very easy to determine. No other colors to really get confused with. However this is only used for a general test. No PH level is gained by using this indicator.

Cabbage Juice is beneficial because it's very easy to get your hands on and relatively easy to understand. You can find charts anywhere online regarding color vs. PH level.

However beneficial these two may seem they both have their downsides.

Hope this helped!

Advantages? Well, Litmus changes from red to blue right about pH7. So you get a conclusive yes/no, acid/base answer.
Red cabbage color changes span the whole pH range. Different colors at many diffferent pH. Plus, I'll bet I could buy a cabbage at Kroger for less than a dollar. That's enough to make a lifetime supply of indicator solultion!!