Not sure I understand your question. Am I right to assume you'd rather use Selenium - but want to understand what you're missing?
Well - Selenium provides means to automate web browsers - and thus used for automated e2e tests. Selenium API has implementations in several major programming languages - allowing you to write your tests in Java, C#, python, ruby, JavaScript and more.
If you already have a selenium-based e2e testing framework in place - you can use it also for AngularJS web-apps. You can also write the necessary JavaScript scripts that, once ran using the webdriver - will let you do all that Protractor does - but you'll have to do it yourself (just borrow from Protractor source code).
Why is it doable? Because Protractor basically took the JavaScript implementation of Selenium Webdriver and wrapped it in a way that makes your life a bit easier when testing Angular JS web apps.
You can see specific explanations in this old post of mine:
http://testautomation.applitools.com/post/94994807787/protractor-vs-selenium-which-is-easier
I'd say that if you:
1. want to write your test code in JavaScript
2. are focused on mainly Angular JS apps
You might want to consider using Protractor. Again - no magic there. Everything they did is there in their source code - so you can just take your picks if you'd rather stick with selenium.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…