That's a very broad question, a bit like asking what car is best, a hundred people will give you a hundred different opinions.
You might want to quantify your question with some back ground such as which brands you've used or investigated? Which brand you trained with, what you liked/disliked about it. Then we may be able to provide some views.
Failing that it's its a good idea to do your own research by reading previous threads on here, there is literally 20 years of recommendations, trouble shooting, advice and discussion, if there is something specific you would like expanding on, or more information then create a new post.