Ti does not have personal bias in a way that Fi does, the only personal bias it has is for logic. Ni and Si have personal biases towards unconscious perceptions.
Logic is the path to see the world in as an impersonal light as possible, therefore the most T type is most objective. The personal bias in favor of logic should not be considered a negative factor because such a bias does not preclude us from seeing the world in a fashion independent to our tastes and prejudices. You can think of feelings and tendencies of perception as items enmeshed within our worldview (basically things that we see within our picture of what the world is like), yet logic is outside of it. It is a way to see the world, yet it does not interfere with the vision because it is the vision itself. Logic, as famously known leads us to detach, or remove ourselves from the picture. To be objective means to see the essence without relying on your own perspective. Thus, if you can remove yourself from the picture that renders you objective. T is the property that leads to detachment, therefore it is the most effective path to objectivity.
Extroverted Thinking is less objective than Introverted Thinking because it is less of a property of T, therefore less removed from the picture. Thus, to be less removed from the scenario means to be less objective.
The salient factor of objectivity is 'Thinking' the rest have very little relevance. To answer the question of which type is most objective we have to discover what type is in closest affinity with their thinking faculty. An example of this would be that both Extroverted Thinking and Introverted Thinking make decisions based on logic. Personal biases have almost nothing to do with the thought of these two types. We should not even consider the matter. Personal biases you can associate with mostly F, and to a smaller degree with our unconscious perceptions. Therefore the less F the type has, the less he is influenced by his personal biases. S is more biased because it does not have a conscious notion of one's inner thought like an N does. An N can be judicious about what perceptions to gravitate towards because he has a vision thereof. Though the S is almost always forced to accept whatever unconscious tendencies that be. Which is why for instance, we notice SFs are more likely to be superstitious than NFs. STs more than NTs---because the latter are more likely to be judicious about their perceptions. Moreover, Sensing is in closer affinity with our nature, it is a property of our impulse. One that we cannot subdue with our minds. Yet, N is more malleable in that regard because it is more of a property of the intellect, therefore more easily extricable from our natural biases. Thus we more naturally long for food and water (S)--along with further ramifications of such tendencies, this we can do little about. However, we much less naturally long for ideas, for instance materialism over ontological idealism, empiricism over rationalism and so on. We also see that Extroversion, along the lines of Sensing is in closer affinity with our physical nature because extroversion is closer in tune with the external world. Thus, we see that Extroverted philosophers more easily gravitated towards materialism rather than idealism, as they took the external world for granted. The Introverted mind is more malleable because it is closer to the property of the intellect rather than impulse. Here we notice that introverted philosophers had a much easier time concocting a system where the realm of mind held primacy over realm of material entities, or vice versa. Yet Extroverts could hardly imagine the material world being non-existent. This evinces the higher propensity of Extroversion towards inability to extricate from bias, and Sensing along the same path.
So in summary, what we have is:
1) Thinking is the primary path to objectivity because it allows for us to remove ourselves from the picture
2) Attunement with mind/internal focus is the secondary path to objectivity because, as property of the intellect it is more easily controlled by our conscious and thus places us in the position to overcome our natural biases.
Thus, we see that the INTP is the most objective type because of property 1--Thinking, and because of the most intense focus inwards. We know that the INTP is the most internally focused type because Thinking is the most 'tough-minded' approach towards decison-making, therefore most intense focus. Thus more internally focused than Introverted Feeling for this reason. And more intensely internally focused than Introverted Intuition, as Introverted Thinking--as a judging function is clearly directed inwards, whilst the Ni 'dabbles'. Conversely, we see with Te of INTJ for example, a stronger external focus than for the Ne of the INTP.
2)ENTJ (intense thinking preferrence overrides their external focus, moreover Introverted Intuition, as a property of mind, highly intellectualized--therefore in the position to subdue our biases compensates).
3)ENTP (Stronger Thinking preferrence than of the INTJ, Ti>Te)
9)INFJ (Ni--property of mind, plus Ti)
11)ENFJ (Ahead of INFP Ti>Te, or in other words Ti is simply more T)
So, here we see that T is a salient factor and N(or property of mind, inner focus) only takes over when we have a big discrepancy, comparing a Sensor to an Intuitor. Yet, however, the T factor holds primacy in almost all other situations, as we see that the ENFJ is ahead of the INFP because of the stronger T despite the INFP having a firmer grasp of his/her biases due to introversion.
*In regards to the lack of objectivity on behalf of Sensation, we should take note of how Sensors are more likely to cling to beliefs they were acclimated to, and at a later point view new notions through the scope of the perspectives they have situated themselves in. Whilst Intuitives are able to 'clear their minds', and tackle new ideas from a fresh perspective. This I argue is by virtue of Intuition being closer to the essence of mind therefore more easily controlled by our conscious intellect.