There are several measures to indicate the quality of a journal. In philosophy, there seems to be some degree of consensus on the relative prestige of journals, e.g., most would probably agree that Philosophical Review is a better journal to publish in than Unknown Local Journal of Philosophy. Here is a list for general philosophy that is, I take it, not too controversial. Here is a list of both general and specialist journals. In Google Scholar you can find citation metrics that measure the influence of a journal by counting its citations (see below the fold for the top 10 philosophy journals according to citation count).
The calculation, done using an entirely automated process, provides the h-5 index. This index measures the largest number h such that h articles published in 2007 to 2011 have at least h citations each. For mature, established scholars, the h index is a fairly reliable measure of consistent output and influence. It is not a good measure for young scholars (a young scholar could be very influential, say, by having 2 articles that are each cited 100 times, such a person's h-index would only be 2).
There are the occasional Gettier-like scholars who have just a few papers that are cited hundreds of times. But for most people, who have a larger output, the h-index does fairly well. The following list gives the top philosophy journals according to their h5-index (see here for a larger list).
- Philosophical Studies
- Mind & Language
- The Journal of Philosophy
- Journal of Consciousness Studies
- Philosophy Compass
- Philosophy and Phenomenological Research
- Phenomenology and the Cognitive Sciences
All these have h5-indices equal or larger than 17, i.e. at least 17 articles published in 2007-2011 have at least 17 citations in current publications that are indexed in Google scholar. I thought a few of these were surprising, especially if one assumes some correlation between ranking and influence (of which the h5-index is again an indirect measure). Prestige can be the result of many factors, e.g., how difficult it is to get published in the journal, or perhaps the prominence of papers older than 5 years as classic readings in the field.
Perhaps my biggest surprise was the ranking of Synthese on (1). Synthese is a nice journal (I have published in it too), but I don't think it would rank very high in terms of prestige. Perhaps this high place can be explained by two factors: Synthese (like Phil Studies, which is on place 2) publishes many papers, so it is not surprising that they have a higher chance to get cited. As Simonton observed, influence (in scholars) is often a matter of quantity. To take an analogy with evolutionary theory: if you have more offspring, you have a higher chance of producing offspring that will propagate your genes, but you will also produce more duds. Perhaps Synthese and Philstudies have comparably more duds than, say, Noûs).
On place 3 we see Mind & Language, which is a specialist journal. I think its influence can be explained by the fact that it is also cited by people outside of philosophy, such as cognitive scientists (who publish in high quantities). This can, I believe, also account for the high rank of Phenomenology and the Cognitive Sciences (10) and Journal of Consciousness Studies (7). The market is bigger for such interdisciplinary journals.
Philosophy Compass publishes only accessible review articles for a broad audience. Given that review articles get more citations, this can perhaps account for its 8th place in the Google Scholar citation ranking. In an article entitled "How much better are the most prestigious journals? The Statistics of academic publications" (Organization Science, 16, 2005), William Starbuck writes "Citations of individual articles correlate [positively] with articles’ lengths, numbers of references they cite, numbers of coauthors, and nonuse of mathematics. Theoretical discussions attract more citations than do empirical studies, and general-interest articles attract more citations than articles on specialized topics". Some of these observations may explain why Phil Review is only on place 17 (behind journals like Phil Psychology and Ethics), and why Analysis (with its short papers) is on place 18.