I own both knives.
Which one you "should" buy depends on how "feel" about your knives and how you intend to use them. I am very cost conscious and always prefer to keep my knives in "like new" condition whenever possible. So, I will not use an expensive knife when there is a cheaper one available.
Are you planning to just carry your knife as an EDC and use it only to cut paper and/or boxes. Then, buy a Native.
Are you planning to subject the knife to "hard" use? Then, buy a Tenacious.
Not because the Tenacious is "better" but because you can buy 2-3 Tenacious knives for the cost of a single Native. You can use and abuse them at will and w/the cheap but still relatively durable 8Cr13Mov steel, you can do most tasks w/o any difficulty. You can easily resharpen the blade when it gets dull and when the knife is used up you can just toss it out and buy another. This is why I'll never use any knife costing more than $5-10 to cut a box, when I have a cheap box cutter or utility knife costing $1-5 that I can use instead.
But, if you are not as cost conscious as I am, then go ahead. Buy a $100-160 Native and beat the heck out of it. It should stand up to the tasks well.
Frankly, I don't think you can go "wrong" whether you decide to buy a Tenacious or a Native.