The further away from a wall the better.
Mine are about 1.5 feet from the wall. 
Wouldn't want them right next to the wall... as you'd get massive bass build-up

If you have a small space for mixing/listening, there's really no other option than putting the monitors close to the wall.  Anything closer than 3 ft is generally a problem whether you have rear ports or front ports....although rear ports are worse in that situation.
 
if you can find monitors that have crossovers, that will help especially if you get a sub.  Then, you're removing some of the problem from the source, and offsetting with a sub.  The sub I mentioned earlier is a front port design.  That was my solution to the rear ports of the monitors and small room issues.  My monitors are only 1ft from the wall, but I have a treated room also.  Without having to "get used" to the problems during mixing, my mixing results are better now and take less time/less iterations.
 
Dave

I'm using the Sub with the HS7s.
No problem with 1.5' from the wall.
 
If you ever watch "The Night Shift", you'll hear music that was mixed on HS7s with matching Sub.  

Soon I will be putting up my new studio building, it will be a larger, out building, and the size if 14 X 24, which will also allow for band rehearsals, etc.  So in upgrading monitors, I want to be sure I have something large enough for the room size (it will be acoustically treated, as well). If the HS7 and sub have enough power for that size room, I'm still leaning in that direction. But if the new JBL 308P Mk II are comparable, maybe with or without a sub, there is a great deal on those right now, including monitor stands, and I'm tempted, but of course haven't heard either of these monitors at all.