I use a fair bit of GHQ infantry in my forces. They are really superb in figure quality. I am delighted every time I pick up a stand of my GHQ infantry.
When you are navigating the GHQ (or a retailer's) website, do look for their "individual infantry" or "individual heavy weapons" packs.
They also make older infantry packs that are 8 or 10 figures molded in one block standing shoulder-to-shoulder. I try to avoid those. They are usually described as "company" packs, or sometimes as "squad stands". There are also heavy weapons sets designed during the same period as the "squad stands", that have the gun crews molded with the guns. I find these do not match well with the newer "individual infantry" sets.
All of this can be a bit confusing on 3rd party websites, but if you look at the catalog on the GHQ website they have many nice pictures of everything to help you see what it is that the words mean.
They offer "Sample Packs" that give you a somewhat random sampling of some infantry, some guns and a few vehicles.
They offer "Battle Boxes" that give you two sides, but usually focus just on the tanks.
And they offer "Combat Command" sets. These can be quite useful. The GHQ website catalog usually gives a detailed breakdown of what's in each Combat Command set. Some are tank-focused (usually described as "tank company" combat command sets). Others provide a fair bunch of infantry, a few infantry heavy weapons, a fair number of appropriate mainstream tanks, a few supporting heavy tanks or light tanks or self-propelled guns, some towed guns, some AA weapons. In most cases these will not meet any appropriate TOE, but they give you a quick start on putting together a combined arms force, and in truth many nations mixed and matched sub-units into combat teams or flying columns of various ad hoc form, and units that were in combat for more than a few days were often not operating at proper TOE strength.
It is somewhat difficult to assemble a force at anything like 1-to-1 unit scales with GHQ figures. Their kits are more closely organized for 1-to-several unit scales. You just don't get enough riflemen and LMGs for the number of support weapons and officers. At least, that's my biggest concern.
On a couple of occasions when I was building a new force I started with a "Combat Command", and then added a few extra packs of infantry, tanks, guns, trucks or whatever to get me to the point where I had about the mix I wanted. This allowed me to get a few support weapons without a getting far too many, and then bolster the number of infantry I have to go with them.
Others have also mentioned H&R. I have used their infantry as well, and I still do. The mix of figures/poses you get in their packs are very good -- it is quite easy to build companies and battalions with 1-to-1 (or stand-to-squad) unit scales with H&R.
Their older figures do not match GHQ figure quality, but once you paint them up at this scale you might still be quite satisfied with the results. I do not have any of the newer H&R figures yet, but I am told they look very good.
Hope that helps.
-Mark
(aka: Mk 1)