Velocity and Mayflower make good kit. I have the Mayflower APC for a work rig and love it. Velocity's scarab is nice as well
Another good company that makes about the best sling you can own as well as some very low profile and good pouches and rig is Blue Force Gear. There RACKminus is nice, and I am eyeing the BELTminus V2 right now. The belt pouches are also awesome.
https://blueforcegear.com/
ATS Aegis plate carrier is a nice rig,
http://www.atstacticalgear.com/produ...te-Carrier-V2/
if side armor isn't a requirement and you are just wanting front and back rifle plates Milan is good people, and makes good gear.
http://www.perrozdesigns.com/shop/cl...plate-carrier/
For running multiple calibers HSGI TACO's are awesome, though a pain in the tail to install. If you have the time/ ability to change out your gear, owning a dedicated 7.62 chest rig and dedicated 5.56 chest using the swiftclip system is a good option.
Travis Haley has some real nice chest rigs that can hook up to a plate carrier via swift clips also, 1 a dedicated 5.56 and the other a dedicated 7.62 rig. The rigs are expensive, but by the time you buy a good chest rig, and then pouches, the prices are about the same.
http://haleystrategic.com/store/equipment.php
I get all my armor (Velocity) through Mike at AT. Mike is good people, he will put you on the right azimuth, even if that azimuth is a loss for him.
https://store.appalachiantraining.co...s.asp?Cat=1875
As stated above, my work rig is a Mayflower APC with front, back, and side Velocity IIIA backers and front and back Velocity P34 plates. The plates alone are IIIA and will take a couple rounds of 7.62, but add in the backers and they will stop 1 round of 30-06. That armor setup will run you about $1000, but it's a solid setup.
If you are going to be doing a lot of walking, you will probably get more use out of this:
http://www.optactical.com/tatafilimav2.html with this:
http://www.optactical.com/xharnessmav.html