Having had both, I'll add my .02.
I'd buy the Smith, but not the heavy-barreled lugged one. Here's why ...
1. Weight - Do you want to carry it around in a holster, say as a hunting gun or farm gun? Or do you want something to take to the range with 300 rounds? The reason I ask is, the older I get, the more I like lighter firearms for ease of carry.
2. Strength - more steel = more weight to carry around, and regular .44's are enough power for me. If more power is needed, get a .454 Casull. I prefer to mainly plink around with .44 Spls.
3. Smith quality control, IN MY EXPERIENCE, is better. I was a Redhawk worshipper until my last 2 Redhawks. The first wouldn't function out of the box, and its replacement couldn't hit the side of a barn due to small cylinder throats. These were the last of 6 Rugers I had bought new and been disappointed with quality-wise. I will never buy another Ruger again, they are Taurus-izing their operation.
That being said, the last Smith .44 I had was nothing special and actually had a crappy trigger. I traded it for something I liked better and didn't miss it. I'd buy an older 29 though in a heartbeat.
In case you think I'm biased, you should know I don't own either brand anymore, preferring my Dan Wesson .44 Magnum to the others.