Pork roast Rib Or Loin End ?
Rib end (I assume you're meaning the shoulder end) makes a better choice (IMO) if you're barbecuing, Loin if you're grilling or roasting. Your listing it as "Loin end" is a bit confusing because there are three parts to a loin (blade, sirloin and center) but I assume "loin end" here means the sirloin which has a lot of bone and a lot of fat.
My personal choice, which is not included in your list, would be the center loin.
I would always choose the Rib Roast. To me, no matter the cooking method, they are always tender and moist. I cook mine for 20 to 30 minutes at 450F, then reduce the heat to 325F and roast till done. Tent for 15 minutes after pulling it out of the oven, and it slices nice and clean, the ribs get a little crusty (delicious). I have cooked Pork Loin Roasts the same way, with differing results, they seem to dry out too much for my liking. Here in Edmonton, Alberta in the grocery stores our roasts are referred to as Pork Rib Roast (boneless, or not) and Pork Loin Roast (always boneless) they don't seem to specify the cut any further than that.