I've built both over the the years. You'll probably not notice the difference in performance on a cruiser, only if you were serious into auto-x. I'd still go with tubular arms though.
The factory arms are fine with rubber bushings but seem to squeak when you add poly bushings. If you rebuild, make sure to buy black that are graphite impregnated and preferably greasable. If you were concerned about the stock arm flexing, don't be. Arms are triangles which is the strongest geometric shape and really only bend with extreme force or impact. I raced on them for years. You can plate them if you were jumping off road, hydraulics, running a coilover bottom mount, etc.
Tubular typically address camber issues and provide more clearance to work and look nicer. The bushings are smaller so less deflection, but firmer ride. You can buy them shorter, longer, centerline moved, adjustable uppers, etc. They will fit better with lowering components and typically allow increased turning radius.
The cpp arms are great for cruisers and affordable and use bushings. I have them on my son's c10. I've used POL/WC as well but prefer CPP. As you go up the price range, the bushings will be replaced with bearings and deflection will be reduced to basically zero.