If your Christmas includes ladies in nice clothes and makeup, then brisket is far easier on your guests.
If you're smoking, and haven't done brisket before -- it can be a bit problematic. To do a good job, you not only need good meat and a good recipe, but good control of the process. Obviously, if you've done a few briskets, you know what you're looking at.
Ribs are much easier.
Of the "big" competition cuts, boston butt (for pulled pork) is far easier than brisket to get right.
Turkey smokes EXTREMELY well. Furthermore, you can smoke a 12# turkey in less than four hours at around 250. Most smokers will hold 250 (or close) pretty well.
Baby back ribs take around four hours, spares around six or seven, and a typical butt takes around 12. A whole, "packer cut" brisket (cooks better than a flat), 12 pounds at 240F - 260F, takes somewhere around 16 - 20. An 18 hour cook for an early dinner makes for a very long day -- especially Christmas day.
If you're smoking, you may want to do something of a barbecue sampler, including a variety along the lines of pork, turkey, links.
I'm guessing from your nic that you're in the Los Angeles area -- so you can take advantage of some of the very good Farmer John links -- especially the "Lousiana Hot" and the "Polish." I tried the "mild Jalapeno" the other day, and they were quite good. Plenty of flavor but not much heat at all.
I'm not a chef, so maybe I shouldn't offer suggestions, but am a avid cook, and do a fair amount of smoking different meats.
Since you asked about two popular smoked bbq meats, and you chose ribs however you are not going to be smoking them. It sounds like you want to impress your guest but do something slightly different from turkey or ham. However ribs really shine when smoked, or unless you have some great recipe that you can do from the oven, and since you asking for advice that may not be the case.
So may I suggest something that will blow the socks off your guests and is really easy to do, but a bit expensive. Roast New York Strip Loin. Here is a link to a good recipe. You may have to go to a butcher to get this cut, Costco had some last week. Figure about 1/2 lb per person. I would recommend buying a remote digital probe thermometer $18, stick it in you will know exactly when it is done. Your guest will love you if you serve this cut of meat.
6 pound brisket, trimmed and cut in half.
Dry rubbed w/secret mix, wrapped and refrigerated for 7 hours.
Sweated onions, (2 Large Spanish, sliced 1/2" wide)
Added a couple of TBS Flour, cooked raw out of flour
Returned brisket (on top of onions),
Covered with tomato paste, covered, into 375º oven for 2 hours,
1 large can of plum tomatoes added,
returned w/o cover to 350º over for 2 more hours.