I have a much different experience.
I've used the WDR3600, WDR4300 models and didn't find any problems even on stock firmware from 2013. I didn't face any hassles setting them up. No iptv issues at all or any problems with wifi. Both models are very similar and are supported well on openwrt, at least from AA onwards. I only ran BB and had no problems. The advantage over the rt-n12 is that both tplink models have a better cpu and more memory - 128Mb. Asus stock firmware has better support for multiple guest wifi networks out of the box.

The Asus rt-n16, ac68u are 2-4x more expensive so cannot be compared directly with the tplink models you mentioned.

If I had to get a router tommorow, the tplink Archer c7 looks good. As of 2014, the tplink firmware (as well as openwrt) supports unifi/maxis fibre.

The hardware specs of the N16 is better and it supports more features that the 1043 doesn't have like smb file sharing, torrent client. The AC68 is clearly high end for a homeusers and should not be compared to either of the tp-link routers you mentioned earlier.

I did not bring up the Archer c9 at all in my post. When I talked about the c7 it was not in reference to your earlier post.

The WR1043nd, WDR3600/4300 are popular models which should work with very minor or no issues with Unifi/Maxis at this point. Only user error is stopping people from getting those models up and running.

The WDR3600/4300 models have poor 5Ghz wifi range (and to a lesser extent 2.4G) because the antennas are all shared by both bands I believe. Its still sufficient for normal use. The antennas use sma connectors and are replaceable, so they are handy for mods and diy antennas to improve the sensitivity/range.