So I did a little testing in the single player environment and have come up with a couple ideas:
Stamina is a great stat to have increased. This increases how long you can run, and you will run. This is best paired up with an increase to speed to get the maximum benefit out of this. I recommend boosting your speed to at least 120%. I believe this is enough to run away from most of the faster dinosaurs.
Next up is HP. This is simple, the more you got the more hits you can take, and specifically the more you can take before you become injured. When you become injured you are usually going to die if you cannot heal up fast enough.
Melee damage is a big one for me. I won't settle for less then 150%. The reality of it is your going to be stabbing things alot with your spears/pikes. Guns suck against dinosaurs. I hate to be the bearer of bad news but you probably will never want to shoot your guns at a dinosaur. The advanced ammo for the rifle (level 55 if I recall correctly) takes a whopping 3 iron ingots each to make, and it takes upwards of 20 shots to take down even a Trike. Guns are for killing other players clearly. Bow and Arrows seem to do more damage, and honestly you are better off just using tranquilizer arrows because it will bring them down faster.
Fortitude seems to be a very underwhelming stat to put points into. I have raised it upwards to 20 so far and I don't really seem to see the benefit, regardless of the armor I am wearing. It just seems simpler to carry more water and more food then it is to put points into this stat.
Carrying capacity is nice early in the game, but I feel falls short quickly. Eventually you are going to be riding dinosaurs around. The more that you have on your person the more it affects your poor raptor, and the slower it will move. In my opinion you are much better off ignoring carrying capacity and raising a dinosaur to be your mule. On the other hand, when exploring caves you are not likely going to have your dinosaur next to you, as I believe the medium and higher sized dinos will not be able to fit inside the entrance. The only thing I can think to counter this is building a small outpost near caves, but (assuming your on a PvP server) then there is a risk of people raiding your outpost as I imagine caves will have higher traffic.
Crafting is just utterly useless. It is extremely underwhelming and putting any points into it all would be a waste. Nothing really takes that long enough to craft that would warrant needing it to craft faster.
Food and Water seem like dump stats to me. Carry more food (which has a low impact on weight), and a few water jars and you counter the need for this almost completely.
Now for oxygen. Right of the bat you may write off this stat completely. The problem is I think we might need this stat alot more then we think. There are several resources exclusive to the deeps waters that you need for some of the late game engrams. As of right now, they do not have any sort of breathing apparatus. The only thing you can get to help you with your deep water travels is the megalodons, which should increase your speed underwater. I personally have very little experience with the deep waters because frankly it freaks me out =D, but for now at least this is something to keep in mind when allocating stats.