I personally wouldn’t buy a specific rifle brand or model just based on the ability to run surplus 5.56. Either weigh the consequences and likelihood of issues running 5.56 surplus in your .223 Rem chamber, or pay a smith $50 to extend the throat and leade to a Wylde or 5.56 spec (ridiculously simple job).
If a specific model fits your body, has all of the features you want, and meets a quality point you’re happy with, great. But the experience in shooting one rifle model versus another will be far more substantial than the difference in shooting 223 Rem bulk ammo vs. surplus 5.56 ammo. If you shoot it a lot so the ammo cost is meaningful (which will wear out your barrel fast and give you the option to pick your chamber in 5000rnds anyway), then you’ll be touching the rifle enough to really appreciate the nice things about the right rifle, or really come to hate the not-quite-right things about the wrong rifle. You’re also spending a lot, no matter what, so whining about a small incremental cost increase doesn’t make much sense. If you’re not shooting much so the rifle fit and features don’t matter as much, then the ammo cost is low either way, and a small difference in price wouldn’t matter much either. I certainly wouldn’t shoot a rifle I didn’t love just because I could save a nickel per round.
Pick the rifle you want, fix the chamber if you insist, and shoot it until it turns to dust.