Both options are acceptable. There are many reasons to select a venue for publishing your work such as quality, outreach and targeted audience.
In order to check the quality of a journal you have to examine the impact factor (see for example: http://mdanderson.libanswers.com/faq/26159)
In order to check the quality of a conference you can check for conference rankings according to the scientific field or the ranking of academic pubishers (e.g. look at https://research.usp.ac.fj/wp-content/uploads/2017/06/2016-Ranking-of-Academic-Publishers.pdf )
I prefer to submit my work on journal in terms of its more validity. but if you prefer more iudience, I suggest you to submit your work in a famous conference, since your work will present as a poster or an oral presentation as well.