We've been on Alamy for years, but really started uploading a lot last year when we gave up IS exclusivity. We now have over 3000 there (about 1200 of them are also on the micros, the rest are not)  and are very pleased with the way it's going, with this month our BME already and still 10 days to go.
I keep batting on about this, but if you haven't seen my comments, I think it's a good idea to sort out which of your images are common and which are niche - if there are very few photos around of a certain subject, and you think it's not likely to sell very often, you may as well put it on Alamy or another macro site. The theory is that if a person needs it and it can't be found anywhere else they will be prepared to pay more for it, so why put it on the micros? For example, Sydney Harbour Bridge - common, hundreds of them around, put it on the micros, unless you were lucky enough to capture it in amazing light, in which case, macro.  Another location, known to you but off the beaten track - macro. When it comes to gathering dust, lots of images gather dust on the micros, too!
I would say that everything sells on Alamy. We have a lot of travel, a lot of food, and a lot of what I call "other" - they all sell.
As for editorial, we don't do very well with it, but I don't think we are very good at it! Other people seem to do well, so it must be us!
I would just ignore the best of button - you have no control over it, it's a new thing for Alamy and a work in progress.
If you haven't started reading the Alamy forum, you can learn a lot there, but I would stay quiet at least in the beginning, as some of them do not like microstockers.
Good luck at Alamy, but be prepared to give it a lot of time. You will rarely get the instant sales that you get on the micros.
Hope that helps.

I just said this in another post about Alamy but I'll repeat myself for you - I have some of the same photos on Alamy & the micros - I took a bunch of them off the micros after they were zoomed on Alamy and purchased on Fotolia, which allows the same license as an EL anywhere else. So yes, I think it's a bad idea to put the same RF photos on both - though Alamy allows and even somewhat encourages it. I have photos (both RM and RF) which Alamy has licensed for $250 one day and then licensed to someplace else for $6 or $17 or $27, so it's really a toss-up.  With some I'd have done better getting $28 from Shutterstock for an EL.

I have some RF images that I've kept on Alamy and the micros because I've earned $150-$300 (that's net to me, not gross)+ for the same photo on both micro and Alamy, so for those I'm glad I kept them on both.

I only have about 624 photos on Alamy - hoping to upload a lot more this year as time permits (I only do this part-time) - and I make 2-3 sales per month (full priced sales - plus a bunch of NU which I don't count as "sales" and which supposedly they are discontinuing, though I've had one along with 3 regular sales so far this month, so they've haven't phased them out yet). So don't expect daily sales like you get on Shutterstock and Dreamstime, but one good sale can make a big difference there. These days, many more sales are under $100 whereas in 2011 and earlier most of my sales were in the $150-250 range. Micro prices have certainly affected the entire industry - especially at Alamy which has the same crowd-sourcing concept as the micros, albeit with better prices.

I sell a lot of travel, some editorial and some concept shots - though most of my concept photos are also on the micros and sell there more often. In a few cases I made as much as $295 for a single sale on Alamy of photos that are also on the micros, but each time I sweated that the photos would be returned and licensed elsewhere, which is another reason I now keep both portfolios separate. Deciding where to place which photos has slowed down my uploading a lot, and I'm now just making decisions as to where a shoot will go and trying not to second-guess myself. I agree that more generic stuff will probably do better on the micros due to repeat sales - as do background and other design elements - while more unusual photos that won't sell often are better on Alamy.

Interestingly, the stuff I have that sells best on both are my more iconic travel images - they don't need to be off the beaten path to sell on Alamy, although I've sold some obscure images there too. And I do have several photos on Alamy - both RM and RF - that have sold 2-6 times each, with other photos from the same shoot selling as well.  These are all very different - a few lighthouse photos and other iconic travel photos taken in the US, a purposely blurred model-released business concept photo, some editorial photos of buildings, some still life & other concept shots, and one food photo - so multiple sales there are definitely not out of the question.

I have two accounts there, one news/reportage and one regular stock. Here are the links if you want to take a look:
http://tinyurl.com/ccnoknl
http://tinyurl.com/cqxdldz

and compare them to my portfolio on shutterstock:

http://www.shutterstock.com/g/wordplanet?rid=223261
Good luck!

I've grown weary of seeing XL sales for less than 50 cents, so I've decided to go RM at Alamy.  It was really refreshing to upload my last batch to one site and be done with it, versus uploading to multiple RF micro sites.  Too soon to tell whether or not I made the right decision.

You're welcome!
Good luck at alamy.

Just wanted to thank everyone for their comments on this thread, as I just started selling on Alamy and was wondering what to sell there versus micro versus both.  Great suggestions!