What are some good english pro/con topics?
for example, abortion (good/bad), cats or dogs.
make them interesting and not very common, like animal testing/abortion/gay rights

something interesting like: dogs are better than cats/vegetarian or vegan?

Alright. So, pro's and cons are very interesting topics.They can include many facts and points that prove whether side you can take. Usually, those kind of essays do not need a side to take/a claim to choose. All you need is some imagination, and a bit of star dust that can light you mind. :)

Ideas:-

- Taxes 
- Interest
- Monarchies
- Foreclosure
- School Breaks
- Homosexual rights (this recently happened and many right about it)
- Donald Trump as president.  

Whether or not to be a vegetarian is a good pro/con topic, but pretty common. Here are other ideas I've brainstormed:
The use of nuclear weapons in wars (especially WWII.)
Android versus Apple.
LED versus other lightbulbs.
The use of food additives, colorings, and preservatives.
Gluten as a whole.
GMOs.
Hope this helps!