Hey Gary,
As with most things here I think, search is probably best to really do your research...lots of people debating it multiple times. In fact, there is a short thread in this group on this topic just on page 2 (back in July).
Nevertheless, I think the dreaded answer "it depends" fits best -- where do you hunt, what is the terrain like, how big/heavy is your rifle etc. Personally, for a 90% solution, I like a tall Harris bi-pod, it has worked well for years. Now, I also have a 338-408 and it is too heavy for the Harris, and I only take it to one or two dedicated spots and so I'd use a different set-up there. Also, if I'm walking the forest and need a quicker, shorter-range shot (maybe 200 yards or so), shooting sticks or something taller and quicker to use would be better.
However, at least for me, if I want maximum flexibility and steadiness the tall Harris works (I'm sure there are newer, different things I haven't tried that may work as well or better). Why tall? The ground is almost never flat, and even if it is, there is often brush, tall grass or other stuff that make shorter bipods nearly useless - at least in the places I hunt. Many times elk hunting you will be on one mountainside looking across at another, perhaps just 400-1000 yards parallel to yours. You will almost always be shooting from a slope, and be uphill from your bipod if shooting across. So, unless you have a tall bipod you'll never get the butt of the gun low enough to see most of the hillside across. Then, if too short, you have to start trying to prop the bipod on a pack or rocks or logs (which is fine if you have all day, but see below). Shooting sticks are taller and more flexible, but I can't get as steady as with a good bipod.
I guess, if you are 500 yards or less, sitting with shooting sticks may be fine. However, if/when you step it up to 600-800 yards, I want the butt of the rifle anchored on something besides me sitting, so if it is an impromptu setup, I'm usually trying to get low and prone on the mountainside, even laying to the side, resting the butt on a small pack/light-weight shooting bag or something, while the bipod is nearly at full extension downhill, trying to get the barrel up. I can get much more steady this way (rock solid) than just sitting holding the butt to my shoulder.
Final thought, for anything long-range, you'd think you'd have all day to shoot. They don't know you are there, they shouldn't be rushed. They'll just lounge around and eat for an hour, right? Wrong! Sometime this happens, but it is crazy to me how often times I still have to race (in a controlled way) to get a shot off (unless, it is one smaller, pre-planed space I expect them in, and I'm already completely set up). One of my favorite places I get to watch an entire ridgeline where they may show up anywhere from 70 degrees left, down the valley up to 90 degrees up the valley where it turns and then they can be high or low on the ridge. So, I almost always have to adjust my set-up depending on where they appear. Then, even casually eating, those suckers MOVE. Especially in the morning, they are kind of feeding, but they also have that clock in their head that they need to get to cover, so they usually cover an opening quicker than you think. Lastly, even in a fairly open hillside, you'll be surprised how often they get hidden by a small clump of trees or something. You think you'll have 15 minutes to get a shot, but they keep meandering behind something, and just when you are certain your are ready to unload once they continue their path and clear the tree they are behind, they suddenly turn and head up hill through the trees vs into the small clearing just ahead. Maddening! Bottom line, even undisturbed, feeding, your window of getting a shot off may only be 30-60 seconds sometimes and if you can't range, adjust your set-up, make scope adjustments and get one in the air you may miss out, not always, but it happens more than you think, at least public land where they know they are being hunted. That also means, you can't be there digging bipods out of your pack, switching out one set-up for another, and doing 10 minutes of "gearing up" (maybe sometimes, but often not). I'm sure some guys here will tell you they can throw up shooting sticks, stand, and shoot 'em in the eye at 1000 yards, but for mere mortals like me, for 500 and beyond, I don't want to be supporting either the front or back on my own. My $.02
