Thanks to everyone for their tolerance in putting up with a few basic questions from a beginner.

The new rifle is COLT AR15A4 (1:7 twist, 20 in barrel). Comes new from Colt with one 30 round Magpul polymer magazine. I am wanting to lay in a further supply of 30 round mags. So, for the magazines:  Steel vs. Aluminum vs. Polymer; which is truly the best? And if someone were to respond polymer (for example), which brand / model is top quality (I assume there are differences)?

For these purchases, cost is not an issue. That is, if there is a good reason for cost not to be an issue. I mean, are Colt brand aluminum 30 round mags (5.56 / 223 Rem) really worth $28 per single unit?

Given that I just saw a video made by Colt where a Colt rep is critical of polymer mags, it is interesting that the new Colt rifles come from the factory with a polymer mag. It is also interesting, that as best I can tell from the current Colt website, Colt does not offer stainless steel mags at all.

Colt doesn't make their mags.  Okay does so far as I know but they won't be making mags after Dec 31st.  

Pmags
Okay
Lancer

These are all well known and GTG.  I've had good luck with Brownells 20 round mags and wouldn't hesitate to try their 30s either.

OK SO this question is gonna get some people all excited but its a reasonable question and part of my happy place.
Polymer mags are fine, colt may be one of the oldest manufacturers but sometimes they can be really stupid. and no "their" mags aren't worth the 28$ mostly because they don't even make them Okay industries makes them then slaps the dancing pony on the bottom. Now on to the good stuff.
In polymer mags magpul pmags pretty much own the market and for good reason they just work and aren't terribly expensive. Followed up by lancers which are also good if you can get them at right price. there are other poly mags that are "fine" but realistically you can get pmags for the same price or cheaper than the others so why. I'd recommend avoiding the following polymer mags: orlight, thermold, promag, hexmag, amend2, and
NOW in aluminum mags okay industries pretty much dominates this category youll find them as okay industries, surefeed, or surefeed e2 all work good. there are other companies that make aluminum mags like cproducts, brownells, duramag, the list goes on for usgi spec mags. As long as you have an antitilt follower and the mag body isn't dented or bent you're g2g. I personally find the duramag to be a softer mag and more prone to denting but hey thats just me.
the last group is steel mags. these ones are the pricey ones they are also heavier than the others but a little more robust. Top of the line is the hk mags but at $60 a pop they arent for everyone. elander is pretty good. asc, cproducts, duramag steel come to mind as well.
summary. Colt can be stupid maybe its from riding the pony too long idk polymer mags are fine unless you drift offstream, aluminum mags aka usgi mags are the lightest and readily available, and steel mags sure are great but I'm gonna be real with you I'd bet its unlikely you'll ever need the steel other than just to have.

last time I looked Landbos Armory has MOE Pmags with no window for $8.49.   M3s & window mags were a few bucks more. I don`t work there, just a customer.

If P-Mags are good enuff for .mil they are good enuff for me, and at $8 a pop they are quite afffordable

Pmags all day every day. It’s not even a thought. If I say “I need some mags” there’s never a follow up of “what kind should I buy?”  It’s “who has pmags the cheapest?”

Yep. Pmags is where it’s at.

Outside of wanting an aluminum mag for a retro or clone build, no reason not to use a Pmag.

Gen M3 window are the best but the MOE mags are close behind.

In the early days, I asked for PMags to be included in the care packages from home as I hated the USGI ones.

Now when I buy mags they are usually Okays. I have a couple hundred Gen2 and I'd guess 50 Gen3 Pmags but I'm back with the USGIs, I guess it's nostalgia.

I do keep my 262 ammo in Gen3 Pmags however.

I don't know why, but I've stocked up on more Okay mags than PMAGs, even though I believe that PMAGs are better... But Okay mags won't be getable soon and that's not just because I live in WAshitstain.

@PursuitSS

Been drinking- can you carry the water here please?

great a tool I didnt know existed and now must find and have

I like Okay for aluminum, Lancer for polymer (hybrid technically) & the SHK Korean Mags in steel, those seem to go in & out of stock a lot, but they are cheap enough that when they are in stock adding 10-12 to your cart isn't going to break your budget.

LINK

I am unnecessarily excited about that. Although ngl that looks extremely monotonous to do 1000s of mags with