Going to add my two cents on this one.
The Stag 10:
Specs: This is the real deal. It's 7075 forged, anodized etc as others have mentioned. The specs are there. I also own a few Stag Ar15 rifles and can attest they are solid and generally an under rated AR company.
Design: This is really a basic AR10 design. Equivalent to the gen1 BCL 102 as it doesn't have the fancy boutique features like ambi controls, or the fancy contours that billet rifles often incorporate. It does however have a forward assist. Which isn't needed but is an extra feature/cost.
But... all is not perfect in Stag 10 land. The 6.5 CM offerings for example were much better than the current mediocre 308 offerings just released. The 6.5 ones had a target version with PRS stock, SS barrels and 2 stage triggers. Along with variations of those options. The 308 offers a milspec trigger, Chrome lined 18.5" barrels with 1:10 twist and a magpul CTR or a regular M4 stock.

308 is still generally fairly expensive. I wish they would stop making plinkers. These rifles aren't really super light for CQB stuff so you might do some of it but will likely use your 223/5.56 instead along with the cost of ammo. The current selection will only feed the BS we continue to see where people strive for 1 moa with their 2K plus semi auto 308. It's how 6K rifles were attempting to justify their crappy performance. It's not the reality with the 308!! A good barrel and trigger along with match ammo in a good AR308 will get you in tactical bolt action accuracy. .5 moa is very doable. 1 moa is a mediocre target that I wouldn't even bother to keep. Rant over..
I ended up buying a receiver set and have ordered the barrel, handguard etc. My Stag 10 won't be a 308 lead hose. It should be fun to put together. The latest price drop on the receiver sets was a nice bonus.
The BCL 102:
Specs: Hahhahahah,

Oh sorry was that out loud? Who knows. Assume 6061 as they continue not to tell us no matter how much we ask. Not anodized. I have no idea what any of the specs are on this. I call it hobby gun spec. The MH also had this going for it when they used DPMS parts. So until now, they were able to get away with it and there was no competition. That being said, it's unlikely to be a factor for most of us. I do have some concerns regarding the hardness of the aluminum and I don't know how much the cerekote will help in that regard. My concerns are on the wear points and trigger pin holes/take down pin holes etc elongating with use if the aluminum is too soft. We will only know this after years of use. It's too early to tell if this will ever be an issue with these firearms. But it is a legitimate concern. One that you don't have to worry about with the Stag.
Design: I happen to like the design of the BCL 102 and while I liked the gen1, I actually really like the gen2 even more. Keep in mind, I'm use to AR308 rifles being proprietary. I have both AR10 and AR308 systems with some to no compatibility. As I happen to not mind the BCL 102 handguard since I wasn't aiming for super light etc, I have no issues with the gen 2 design. I find it kind of clever how the contours were designed. Plus it offers the ambi bolt release which is usually only seen in more expensive guns like LMT etc. I like the looks of it. But that's subjective. I like the real features. I also have a latest version though which seems to have the bugs worked out. My dust cover for example is great. The fit is excellent on my BCL 102 as was a buddies who received his at the same time. The cerekote finish was decent and it comes in more colours than black.
Overall I don't think the 102 is done yet. It could have and should have been but... Arms East has left a huge door open. The 102 comes with a barrel that looks to shoot decently once you realize which ammo you should be trying in it. The barrel is a compromise but it's a better one for most users with the cost etc of 308. Also they sent out a few with match barrels that looked to be the international ones that are about to come to market. Arms East/Stag has clearly opted to make their accuracy version the barrel burning 6.5 CM. Not all of us want that. Many of us still shoot targets for fun with 308. As the saying goes, only accurate rifles are interesting. With the Stag 10 in 308 also needing a decent trigger, that extra keeps the gap between the two in price. The prices will have to come down a bit with the BCL 102 to remain competitive. But they can still maintain the Canadian DPMS AR308 rifle spot as the lowest priced and still ok. Frankly DPMS has been very successful in that market. There is no reason why BCL can't be as well.
If buying right now, there is no doubt to
go with the Stag 10. It's a better base and a better firearm. It's unfortunate their 308 offerings suck. Which is why I bought a stripped receiver set. I generally like to buy as close to what I want out of the box. Especially with AR308 rifles as they can be a pain to mix/match. With the Stag I would actually want a lot of Stag parts in my rifle. I bought a complete rifle with the BCL 102 and it did exceed my fairly low expectations. Unfortunately I can't go that way with the Stag. Which means even more money. The BCL I plan on keeping pretty much stock, other than maybe a new trigger. So the price is known. The Stag is likely going to cost me $700 more than the BCL 102. It will be a better rifle, but it won't be inexpensive.
Again if anywhere near the same price, get the Stag 10.