The flat is usually a smaller cut, so it cost less and is usually easier to find in my area. It also takes less time to cook but I prefer the results with the whole packer and the point is actually pretty good.
To me, similar to the differences between cooking a turkey breast vs. a whole turkey. The first is more expensive per pound but cooks faster and has less waste. The second gives you a better variety of meat moistness, taste and texture. I vote for the whole turkey and for the whole packer.
I would suggest getting the whole packer. The point part of the roast is the tenderest by far, and once you do one successfully, you won't settle for just the flat.