All I know is Christ said that "by your fruits you will know them"
You may have just answered your own question. So lets pursue this line of reasoning a little further.
If Christ is the vine and the members of the Church are the branches then it should reproduce in kind. Figs from figs right? Thus it is reasonable that whichever church claims to be Christ's Church (and many do) will both be rooted historically in the original Church and bring forth fruit in kind.
You said that you examined the fruit of both Mormons and the Orthodox and find the Orthodox fruit lacking in comparison (of course I suppose much will depend upon what qualifies as fruit for these purposes)
What did the Lord say would happen with unfruitful branches? Would they not be chopped off? But being chopped off/removed from the tree is not the same as the tree being made bad by the fruitlessness of any given branch.
Can we agree that there are going to be bad actors, disloyal, ignorant, shamefully inadequate members of any human institution, but those bad actors do not in themselves get to define or set the standard of what this or that organization stands for. Consider yourself. You have bad days. You don't always live up to your ideals. Yet some days you do much better, you are more the person you want to be. Should a third party be watching and judging which "days" would you hope most informed that judgement. That's easy, our good days, the day's we are at our best. So why not show that same courtesy to both the LDS and the Orthodox and any other ostensibly Christian body you want to consider? Why not let your opinion be formed by the intersection of 2 things: The teachings of the organization and it's best exemplars. Look at what they teach, and look at those historically and in the present time from that organization who best embody and exemplify that teaching. That is the fruit to examine. Any tree's fruit can be spoiled, but it is the fruit itself, as it should be that proves or disproves the worth of the tree it came from. It is from that fruit that we can see if indeed the tree is reproducing in kind, and what it produces is indeed good and very good.
That is your test. Take the best exemplars of the the LDS faith (or any other you like), and the best exemplars of the Orthodox faith both past and present, set them side by side. If lived out as it is taught will the LDS faith give you the likes of St. Silouan, Mother Gavriella, St. Pasius, Elder Sophrony, Elder Porphyrhios, St. Arsenius, Elder Cleopas, St. Seraphim of Sarov, St. Sergius of Radonezh, Fr. Arseny, St. Xenia of St. Petersburg, St. Mary of Egypt, St. Nectarios, any of the Desert Fathers or Mothers, and this is a very short list and yet it is a list of men and women from the earliest days of the Church to the present who are everyone of apostolic era caliber. These are men and women literally transfigured like Christ, who worked miracles, whose whole life was resolved into a burning dew of prayer.
You will find many good God loving people in other faith traditions, but if you want to know if they are in any meaningful sense "The Church" ask to see their saints both past and present. If you are not being shown lives like those I just named in unbroken continuity from Apostolic times to the present, you are propped against the wrong tree. If any other faith tradition can give you the likes of St. Seraphim or Elder Porpyrhios in the present day then you are very close to the Kingdom of God indeed.
You say you see Orthodox too cozy with corrupt political and social agendas…but America is hardly definitive of Orthodoxy. Look at Russia which boasts an Orthodox culture, which has seeded the earth in recent years with hundreds of thousands if not millions of martyrs. They have recently passed laws to punish "exhibition style" desecrations of religious sites. They have recently passed laws to forbid public gay propaganda promoting that lifestyle. While America makes idols of it's liberties (and is losing them) Russia is embracing it's historic faith and healing itself little by little. It is becoming more and more an overtly Christian nation…certainly Christian friendly. And they are one of the very few nations supporting the persecuted Orthodox religious minorities of Syria during their civil war.
Inspecting the fruit of various faiths is an excellent idea, definitely a Biblical one, just be very sure not to confuse religious activity with the "fruit" of living in union with Christ, for it is that union that enables the Church to reproduce in kind, not just be busy. Remember bad limbs get chopped off, good ones get pruned, and if you want to judge a tree by it's fruit then judge it by it's best exemplars…not the worm bitten casts that have fallen to the ground.
The proof of the Church is not her programs and mission statements. The proof of the Church is her saints…because if what she teaches and ministers is not true, that untruth could not produce divinized human beings.