New bike guidance requested

I have been riding a Specialized Siruus Sport for the last year and spent more time on the road that originally imagined (over 1k Miles). I’m needing some basic guidance on an endurance road bike. I plan to ride 1-2k Miles this year. I’m 6’ and am 285# muscular build. I plan on visiting a couple of shops this month and test Giant, Specialized, Trek and Cannondale. Anyone have advice for a frame suitable for my frame?

 

Consider a hardtail 29er ...

Sizing is always problematic ... in the past, based on top tube length, a MEDIUM 29er would be like a LARGE 26" MTB ...

When in doubt between two frame sizes, I would probably choose the smaller of the two.
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You can ALWAYS fit narrower tires in a frame which can accommodate a fatter tire ...

... a second wheelset may-or-may-not be necessary.​

 

I'm 6'2 220lb and I recommend a Trek Gravel Bike. I talk about if you should buy a Trek bike here (Youtube Link) and I also gave a shoutout to another trek bike rider who also recommends everyone try the Trek ALR 4/5 for endurance rides.