I started uploading to the more popular microstock sites in June.  Here are my impressions so far:

In that time my photos and workflow, or the care I take over them, have improved significantly.  I have also learned the pain of avoiding logos, people, etc, in pics.  I don't think that any of my pics have been accepted by every site.

Earnings are very low, but I only have about 50 images up and it certainly seems that some pics are very much more popular than others, although the most popular pics differ on each site.  It doesn't look like I'm going to retire on the proceeds, unless I get rather more consistent earners.

SS Just got in, on 2nd attempt, but already my pics are selling better here with only 9 pics up than on most of the other sites, despite paying $0.25/download, rather than the more normal $0.3x.  Scenic photos and still lives seem to work better here than on the other sites, which may prefer drawings / patterns / cut-outs.  The site is OK, but does not provide info such as the number of views.

IS High picture standards -- took a couple of goes to get in -- but accept resubmissions.  The reviewers are probably the best of the bunch; it is always pretty clear why a pic has been rejected, and the site has a good community feel (eg, others can rate your pics).  But reviews are very slow -- up to about 2 weeks.  Acceptance rate about 50% (and rising).

FT Low acceptance rate (40%) and poor feedback, so difficult to know what they are looking for. Reasonably quick reviews.  Identity of purchasers available (mostly European in my case).  Faster than average site.  Good stats (eg, views / day -- around 15, in my case)

DT Slow reviews (around 1 week).  70% acceptance rate.  Average sales.  Feedback on keywords leading to a purchase available.

SX Very fast reviews (minutes / hours).  High acceptance rate (rejections mainly for legal reasons -- they are stricter than some other sites).  Average sales. Useful self-promotion features can help sales. Friendly ambience.

123rf Clean but slow site.  70% acceptance.  Low sales.  A bit impersonal.

BS No sales. Very low views per image, if they are accurate.  72% acceptance, usually within a couple of days.  Images ranked by reviewers (OK / Good / Excellent).  Most of mine are Good, none Excellent.  Don't expect a number of my photos to sell, as they are annotated ("blurry, best at low resolutions") in a way that does not accord with my views. 

Thanks for a nice recap of all the sites. I just started uploading a couple of weeks ago  and this kind of information certainly helps!

 I have not tried SS yet, and I didn't get in IS in two tries.  I will try SS only when I get in IS

What is interesting is that my acceptance rate on fotolia, DT, 123rf, BS, and StockXpert so far has been almost the same as yours, although with less files in my case.

Goldenangel,

Worth getting going with SS as soon as you can. If your first submission doesn't get 7 out of 10 through (and most don't) you're out of the picture for a month. Might as well get the initial batch over with.

Make sure that you have plenty of variety in your initial 10 and take note of their do's and don'ts. If you have Images that have been accepted at DT, FT and SX they are probably a good bet with SS. They are not as strict as IS.

Thank you for all your advices guys. Yes, I have a few images in mind for SS already and I'm gonna submit them in the next few days. Let's see how it goes...

For me SS is weakening every day, but others are stronger, especially DT....

BS No sales. Very low views per image, if they are accurate.  72% acceptance, usually within a couple of days.  Images ranked by reviewers (OK / Good / Excellent).  Most of mine are Good, none Excellent. 

The image ranked by reviewers information, where is this located please?