You are picking 2 completely different calibers here... I would never think of comparing the 2.. Personally I love my 17hmr.. Crazy accurate.. But I would only use it for rabbits and squirrels.. A 223 going though a rabbit would destroy all the meat..
As for target practice.. 50-100 yards 17hmr
100yrds plus 223..
I would assume the 223 has a flatter trajectory since its moving twice as fast as the 17..
At 100 yds, they are so close as to be the same. Zeroed at 50 yds, the 17 HMR (17 gr poly tip) will strike 0.3 inches below aim point, the 55 gr .223 will strike 0.5 inches below. However, at ranges over 150, the tiny little .17 HMR starts shedding veocity pretty quickly, and the .223 will be flatter.
The little .17 Rim fire is not a Western Coyote rifle. These are big heavy coated animals taken in open often windy conditions. Why shoot any animal larger than a thin skinned rabbit or rodent with a rimfire?