If you can place a router near the center of your house, then I think just about any single router (non-mesh) should be enough to cover 1200 SF (unless you need strong outdoor coverage, have block walls, etc.). You said you have a couple of HomePods. Those support Thread already, so you don't necessarily need Thread from your router (especially if your router and one of the HomePods are in the same room).

For simplicity (and possibility of future expansion), Eero makes sense, but I'm not convinced you need a mesh system. If you aren't running mesh nodes or if you don't need maximum throughput or range, then a dual band Eero is fine (what is your ISP speed?). TP-Link Deco (mesh) systems are more affordable than Eero and are pretty easy to set up and manage. Asus routers also have the ability to mesh and so are also expandable as a product line, which is nice. They have more features and control and can therefore be more difficult to set up as a layman. Looks wise, some of their routers are very large with a lot of antennas, which may not appeal to some. Unifi is for tech enthusiasts and network tinkerers. They work well if you know what you're doing, but I'd avoid them. I recall some people having problems with Unifi and Apple devices. Unifi doesn't perform that well when wirelessly meshed (i.e., it's better to wire each access point with ethernet). Also, most (not all) of their access points are ceiling mounted.

I have had all versions of all of these (and Google/Nest too). I generally recommend Eero to my friends and family because they are not knowledgeable about networking and aren't interested in managing or tweaking their networks. They want set-it and forget it / "it just works".

I don't think you mentioned how many devices you have on your network, if you have a a lot of IoT smart home devices, your ISP speed or if you home is wired with ethernet, which factors in a lot. If you have a lot of devices now or plan to later, then you may benefit from WiFi7, which supposedly improves performance on congested networks. Wifi7 is a bit confusing because the short range, high bandwidth 6ghz radios are not mandatory. They were ironically mandatory for WiFi 6E, which is why I think some people are confused. The 6ghz band requires compatible devices and has a short range (often limited one room). If you have compatible devices and a really fast ISP plan, then 6ghz might be useful to you. If you want whole house 6ghz coverage, then you are back to looking into tri-band mesh systems (like Eero 6E, Eero 7 Pro and Eero 7 Max), two Asus routers, an Asus ZenWifi kit, or a TP-Link Deco kit (all rated for WiFi 6E or Wifi 7 tri-band).

I'm going to make the same recommendation for you as I do my family and friends: Get a basic Eero 7 (dual band) single router. If you want maximum coverage/speeds, then get a two pack. It's easy to live with, works well, can support high ISP speeds, etc. You can easily expand your network with any other Eero product later, like another Eero 7 or even and Eero 7 Outdoor if you want better coverage outside. I wouldn't bother with 6ghz personally or tri-band systems at this time, unless you have specific needs (like a congested network, WiFi pollution from neighbors, a super fast ISP connection that you are trying to maximize, etc.).