Weight is the first consideration in my opinion & ammunition is the 2nd. As to bbl. length, any thing beyond ~4" makes it a royal PITA to carry when seated in any modern conveyance. The gun is pushed up into your short-ribs!
A 4" bbl'd .44 Magnum, in Smith's "N" frame models or one of the other makes, is not a light weight proposition. I've carried Ruger BH's in .44 special with 4-5/8" bbl's and found them far too heavy for all-day carry.
But you might like a used Smith .44 Magnum Mountain Gun with a 4" tube that'll fill the bill and weighs only 39.5 oz. unloaded. They're often on GB, but are becoming rather expensive of late.
Another outstanding choice is Smith's Model 69, a 5 shot .44 Magnum with a 4-1/4" bbl. that weighs-in at 38.7 oz. I own the M69 and have found it to be one of the most accurate .44's I've had over the years, and it's light weight makes it a joy to carry on the belt.
Ammunition selection is a consideration in any .44 used for self-defense as you no doubt know, with over-penetration a big factor. Light .44 Special loadings, designed for protection might be the best choice, and will offer faster follow-up shots if necessary.
JMHO & YMMV, Rod