District roads, field roads, forest pathways. Sometimes downhills, pushing to the hills. How to do it? Low weight, yeees. 2x28 to go. V-brakes are out, follow disc brakes. Headroom just right, for higher obstacles helps low weight for lift up. Gravel, if you want, connects attributes from road and offroad machine.
28" or 29" are the dimensions of today, which give the main direction of cycling. It means available quality components - rims, tires, disc brakes. Bigger wheels are better to drive, better goes thru the bumps, 35-40mm tires/tubeless/tubulars give us enough comfort in combination with reasonable rolling.
And the top one? Clear, carbon, tubulars, disc brakes. 7,2kg. Go to the countryside ;)