I use both the 24" Ultra Bull Barrel, and a 22" Standard contour in 223. Both shoot great.
But if I were to have only 1, it would be the 24" Ultra barrel. Even though it is a bit heavier and just a tad longer, it's my go to gun. I can always trust it to deliever. Plus it's the nicer of the 2, sporting some new lam's
It's been great for long range targets as well as varmints.
Still I love the little 22" as well, I have it in a synthetic stock with a 3-9 Mil-Dot Tasco for a truck gun. It's very light and balanced. And even though the scope isn't top notch, it fits this packagae very well and has held zero ever sense I got it in a trade.
Another thing nice about a 223 is the ability to handload it with reduced loads. Something I have just started experimenting with, and it's a ton of fun. Anything from 22LR, 22Mag, and Hornet velocities to full power 223 loads. It's so versitile.
-Aaron