this is a question for those who buy images.  If you are a photographer who wants to 'guess' why buyers buy at istock, please start a new thread.

For those of you who buy images (i think they are a few designers on here), I am really curious why you buy at istock.  They sure seem to have the largest market share for buyers, but they don't have the largest market share of submitters and I am wondering how they managed that, or what attracts buyers??

Even though I am a submitter, I have purchased files from iStock. Most of what I have bought has been flash files for my website since I know nothing about flash. No other of the big stock sites offer that. Plus it is real easy to buy credits with your account balance.

I buy rarely, but when I have bought it was to get holiday borders for my Christmas cards.  I bought mainly from DT, but also picked up a couple of exclusive ones from IS because there was nothing very similar elsewhere.   

FWIW, those of you who do borders, there is room on the other sites for some more Christmas borders, particularly holly, pine, and especially poinsetta...

1. They often have just what I'm looking for among their exclusive photos, but trust me, I usually try to find it elsewhere first

2. I always buy for web, so I like the price of the smallest size: $1. A subscription is out of the question and some other agencies charge much more than that for a web-size photo

3. Being a contributor I know they take more care than any other agency to ensure their files are legal, which gives me a lot of confidence when I publish

4. I keep getting free credits whether from a promotion they're doing or from the code on the back of the staff business cards

Im i photographer only, but sometimes i had to buy photos for my friends designers. Istock is last place where i would like to buy, but at the end most photos i bought  there. They have better quality  especially if you need for printing, easier to find what you looking for. recently i bought photos from 123rf and they are not suitable for printing since photos of 12MP(not isolation) was heavy only 550kb completely wash out details. from Dreams time i bought two photos, they are unnecessarily oversharpened with halos, also not suitable for printing. I bought one from Sxpert and it was ok. Against my will I had to buy 8 photos from Istock and all of them are good.
 If you have decent budget for project, price difference is not that huge if you could get what you want.

I used to have a corporate account on istock for a company I did work for. We chose istock because of the easy ability to add credits when needed and the general overall quality. Not being "regular downloaders" we didn't want to get sucked into subscription plans we would never fully utilize.

Here is a short list of things I bought. Note that these are "specific" searches as opposed to flowers & sunsets & stuff. In case some of you wonder what some buyers look for.

Oil platform - style of the platform mattered

A certain type of cell tower (it was the construction method in the tower that was important - only one style would work)

5 year old (approximate age) smiling clean cut blond boy wearing a red shirt, looking straight at camera, isolated on white (as if he was about to play with toys). In the image, I needed to comp in a new toy prototype. Found exactly what I wanted on istock.
 
Workboat or barge with railing

One of those red UK phone booths on white or one I could easily cut

Particular shot of Canada Flag. I needed a sort of a slightly downward view to comp into an image to replace a USA flag. Was hard to find - that's why I have a problem with reviewers who say "too many of this". If they are good, never too many.

A vintage toaster

Single knife and fork vertical aspect - wish it would have been shot on black with proper studio lighting, but took the isolated on white and fixed it.

Good looking raw steak

A cello wrapped gift basket - was for web so contents did not matter too much. Fluffy cellophane wrapping and big bow were what mattered. Had to change color of bow.

Antarctica blue water, blue sky, and icebergs

Pile of diamonds or CZs (no luck on that one - they were all crap on every service - wound up hooking up with a gem broker and shooting them myself)

About 90% of the needs were fulfilled by istock during the course of my relationship with  this client. This started about 2005.  The money didn't matter much as long as what I needed was available.  We looked at Shutterstock, but at that time, once you got past the first 3 or 4  pages, you really started seeing "the crap" and we decided against it.Quality much better overall now, and at every service.