I like both. Both have shall we say "redeeming qualities" If I couldn't have my first choice a 30-30 or 44 mag then I would have to go with the 38/357 while my preferred field pistol is a 45 colt the wife has a .38 and I can use same .38 ammo in .357 field pistol. So the advantage in reduced gear and single ammo wins, barely. I really love the 45 colt round but would be more likely to toss a 38/357 lever gun in the trailer when camping along with a single box of 38 ammo. ok maybe a small box of 357 mag ammo would find it's way into my shaving kit or duffle bag.
In the end it comes down to shared ammo and shared speed loaders. I would really not want to carry a 45 colt side arm and 44 mag rifle. Sorting that brass is tough wearing reading glasses. In a rush too easy to grab wrong ammo between 45 and 44 mag.