There are many criteria. However, the dilemma for 'emerging' journals is that they have yet to establish some of the criteria - especially around reputation. Amongst the most common would be:
- history and reputation,
- reputation of the Editor-in-Chief, Editors and the Editorial Board. This would be important for emerging journals,
- quality of the reviewers - and timeliness of reviewer feedback,
- timeliness of publication (in press) and actual from acceptance ,
- a clearly defined journal scope,
- clear instructions for authors,
- contentious or not - one of the main factors that individuals look for (or institutions prefer) is citation scope, Impact Factors, Cite Scores, rankings etc.
Hisham, depends on your purpose. The quality of a journal to me is the type of readership because I want to reach a certain audience-therefore practitioners, open access, newsletter, style of language and technical content. I avoid the academic obsession with impact factors.