If muck arctic's arent keeping you warm the issue is not your footwear per se. Not that they are the best or warmest, but they are pretty darn good and pretty darn warm, and an incremental difference in insulation above this isnt going to suddenly flip a switch magically making you go from numb to toasty warm. I havent used overboots to hunt in, but hearing how people are using them I'd go out on a limb and suggest that has a lot more to do with moisture management than it does with how "warm" or how well insulating those are, and is worth looking into as one way of achieving warmer feet.
I guided ice climbers for many years, and saw a ton of people with cold feet issues. Usually their feet are fine, there are 3 main issues in play that I see--1) overall heat management, 2) moisture and 3) circulation.
Start with making sure you aren't cutting off the circulation to your toes and feet--if you compress the blood vessels across the top of your foot you WILL have cold feet, no way around it. So make certain your socks are large-enough to not compress your feet, if you wear 2 pr of socks make sure the second pair is oversized enough to not squeeze the first pair too much, etc. Make sure your boots are large enough with all of your socks on to not reduce circulation, and not laced too tightly to reduce circulation.
Next, if ANY part of your body is cold below skin-level 1) put a hat on and/or 2) add a layer on your torso. Your body is trying to keep your brain and your vital organs at temperature, so as soon as it starts getting cold it will reduce blood flow to your extremities (hands and feet) to compensate. You lose a huge % of the heat from your body through your head, so this is usually the easiest and fastest way to manage how warm/cold your feet and hands are. If you are moving and want to stop, throw on the hat or a quick insulating layer while stopped to avoid getting chilled. And shed the layers BEFORE you start sweating--it is NOT a good idea to just bust out the approach to your stand with all your warm clothes on and get all sweaty if there's any issue with staying warm. This is overall heat/moisture management 101, but I'd say it is a learned skill and 99.9% of the hunters I have hunted with east of the rockies, unless they have a cold-weather athletic background or specific training in cold weather (military mtn warefare school or equivalent) are clueless about managing their own body temperature to stay both warm and dry while exerting themselves, so keep it in mind and practice, it takes being able to anticipate how you are personally going to react to exercise in cold weather.
Last, either keep your feet dry, or at least keep the insulation dry and any moisture trapped against your foot--the old military bunny/mickey mouse boots were rubber on the inside so your feet come out soaked and looking like white prunes, but the insulation never got wet. it works. Or, keep your feet and insulation as dry as possible--change socks. One of the biggest ways I get cold feet is from the drive to where I'll be hunting--when I go ice climbing I usually drive there in my street shoes (around here cold wx street shoes are sorel's or 1600g lacrosse, etc), then when I get there I change my socks and put my climbing boots on, and start the trip with dry feet and socks. Even if I wear uninsulated sneakers with no heat to the floor of my truck, my feet still sweat on the drive, so this makes a difference for me personally.
If you still have cold feet you may have a circulation issue, in which case it's not an issue of insulation, it's a physiological inability to warm your extremities. In this case I dont know what choice you have other than adding external heat, i.e. heat packs or electronics, etc. I have never had to do this and I loathe relying on this stuff, but people do use it and it works. You can get heat-producing footbed liners, etc, just again make sure you dont cut off your circulation by putting too much junk in your boots.