I have the exact Troy Bilt mower you're considering-- I chose the Troy Bilt because I wanted a nice engine (I was buying into Honda reputation) and didn't really want self-propelled (no need for it, less to break, more power going to blade not having to drive wheels).
I really like the GCV160, it's smooth quiet engine with good power. Noticeably quieter than other push mowers I've owned. Always starts in a pull or two. Mine has the "auto choke" lever that once you set, it pulls the choke off automatically. There's been a few times that hasn't worked quite right and I had to pull the choke off myself, or it pulled choke off too soon... Wish it had a manual choke, that might be my only complaint.
I've owned the mower since 2010. They still make them, I see the same mower on store shelves to this day, I bought mine for $269. I've since moved to a house where it's not practical to use a push mower (riding mower is a necessity.) So the Troy Bilt has been shelved and only gets used when I need to clear fields or do heavy duty stuff I can't take my rider into. I rigged the governor so that I can set engine speed above and below the preset speed (mower has no throttle control out of the box)-- I've used it at engine speeds well above what it was set/designed for, and you just can't kill the thing. I would buy another Honda GCV in a fast second.
It is their residential stuff, but it's certainly not garbage. All these small mower engines (unless you spend big bucks) have aluminum bores, standard bearings, all the attributes that make them a "residential" engine.