Archer C7v2 has long been preferred as a nice and stable router. USB is slow and NAT caps out at around ~500mbps but is otherwise very good (there are a few patches around that improve this slightly). The WiFi driver for 802.11ac has improved stability(no crashing after 2 days) in trunk but has not been backported to stable yet. Range is also excellent (in my opinion).
If faster USB is needed, the recommendation is the Linksys WRT series of routers (new ones). Avoid the WRT1900ACv1 (keep rebooting, watchdog driver bug i think). WiFi is pretty stable now. One really nice benefit of these routers is that most of the drivers have been upstreamed in the kernel and thus get love from the kernel community (enhancements and bug fixes). Not so with the other popular routers.
I used to run DD WRT, but got tired of fighting weird issues. Looks like from the comments to your post there are still issues out there. I ended up switching to a ubiquiti AC Pro for WiFi and am about to buy a USG to replace my old router. If all you are looking for is rock solid performance and reliability that is still fairly flexible I’d go with Ubiquiti. If you want to tinker or are really passionate about running open source then obviously LEDE is a decent choice.
I run stock LEDE on Archer C7v2 and have had zero problems with it (I ran OpenWRT before LEDE made a stable release). I could buy a Ubiquiti gateway and AP, but C7v2 is less expensive and gives me an appreciation for embedded device programming. I have had trouble experimenting with advanced features such as band steering, mesh and multi-WAN/load balancing in OpenWRT/LEDE though, so if you plan on using those, I agree Ubiquiti is a great choice.
AIUI the Archer C7 requires some tricks to get around recent FCC enforcement which bans citizens from installing their own router firmware, cf. https://pappp.net/?p=1525
I've been using LEDE on my C7v2 for 6 months now and have not had any issues. I switched firmware because the mac address reservation for dhcp wasn't working in the official firmware.
There are almost no good modem+router combo devices on the market. There also aren't open-source drivers for the modem half of any modern modem+router combo boxes, so they won't be fully functional with OpenWRT.
If faster USB is needed, the recommendation is the Linksys WRT series of routers (new ones). Avoid the WRT1900ACv1 (keep rebooting, watchdog driver bug i think). WiFi is pretty stable now. One really nice benefit of these routers is that most of the drivers have been upstreamed in the kernel and thus get love from the kernel community (enhancements and bug fixes). Not so with the other popular routers.