Get both and practice. Shoulder holsters in my experiance are harder to conceal. Unless its winter and you can wear a coat or thick sweater. I typically carry "strong side" (right side since Im right handed) IWB (or inside the waist band).
This for me is the easiest to hide and draw from but its also what Ive practiced the most. If you like shoulder carry better and you can hide it then stick with it.
So, Get some decent holsters of both styles for you weapon of choice and practice and see which one you prefer.
When I originally started searching holsters to find the right carry method *for me*, I found shoulder holsters to be fairly cumbersome and awkward.
For "ease of draw", I'd have to vote for "Outside Waistband on strong side".
One disadvantage to any cross body draw holster is if the attacker is close enough to you, it's easier for them to control your arm and prevent you from presenting your weapon. With a strong side draw you can turn your body to create a little distance between your weapon and the attacker.
Unless you are wearing linen pants and loafers without socks, you shouldn't be using a shoulder holster unless you are in a very specific set of circumstances. It isn't the 80s anymore.
Seriously though, if this is an honest question, you would be better served to get some professional training before making a decision. A good holster will cost you anywhere from $50-150, a belt can cost $50+, mag carriers $25+. Before you end up with a box of holsters you don't use, you'd be better off spending a little cash and getting into a class that has some loaner gear. You'll come out ahead in the long run.
I generally carry strong-side concealed, but I have a "special circumstances" caveat to what seems to be the preferred method of carry. If you typically spend a lot of time seated in a vehicle, a shoulder holster may be preferable to strong-side carry. You will seldom find a helicopter aircrewman or a fighter pilot wearing a pistol in anything but a shoulder holster. In cold weather, it may be easier to get to a pistol in a shoulder holster than to dig under layers of clothing for a pistol mounted on your strong side. If you drive quite a bit, you might consider a cross-draw belt holster for the same reason.
I have been looking into this question myself, and from what I have seen, I think another consideration is where you would be carrying.
Case in point, I work in a psychiatric hospital setting, in a shirt and tie. 1) I can't have a weapon in the hospital with me, for obvious reasons. 2) It can get hot enough in my monkey suit, and adding a jacket is sometimes just too much. I think a decent IWB or OWB strong side holster is probably what I will be aiming for, unless I find a decent shoulder holster that doesn't attach to my belt for car use- the joys of being a on call employee in the middle of the night...
Like others have said, I carry strong side or in the IWB small of my back. I have a shoulder rig but haven't been able to conceal it too well so I don't usually use it. I have several paddle style holsters but find myself using my N8 squared IWB the most.
To answer the op's question it would be faster for a hip holster over a shoulder one IMO.
I believe strong side OWB is the safest and easiest to draw from. I have, and still due use ankle carry when circumstances are right. I have used and would like to have a shoulder holster for some previously mentioned reasons.
Another point that should be mentioned is what firearm are you carrying. For example, I have three different holsters for three different guns:
For my little Beretta Minx, I tend to keep it in a little IWB holster, or just a straigh pocket carry.
For my Smith and Wesson Snubbie, a strong side OWB works wonders for me.
And for my Ruger Security Six with the 6" barrel, I have a bandolier holster that can actually be adjusted to hang anywhere from under my armpit to right at hip level.
They all work, but because each gun is different, your carry method has to match your weapon.