I doubt we can really know what Jesus truly felt and taught, since we have only third-hand and further removed accounts claiming to represent what he did and said.
If there is any truth to be had from reading between the lines of those accounts, and perhaps reading them against the earlier (and likely more reliable) accounts in the Talmud, my guess would be that the historical Jesus was not "anti-Pharisee" per se, so much as in disagreement with them about certain theologies and priorities of practice. He himself was likely a renegade Pharisee, so he was unlikely to be 100% in opposition to them. He was almost certainly opposed to the corruption that plagued the priesthood that time: but then again, the Pharisees were also opposed to that corruption.
They were absolutely strict in their adherence...but unfortunately it was all an 'outward' display of piety.
This is simply inaccurate. Pharisaic law is in fact extremely flexible and nuanced, and geared deeply toward application in mercy. The Rabbis repeatedly give us principles for tempering judgment with compassion.
Moreover, in their discussions of observance of the commandments, they frequently refer to matters of motivation and intent, and questions dealing with internal matters both as provocation to and result of action, and the spiritual meanings and ramifications of observances. The way they understood Torah and observance was in no way, shape, or form merely an outward display of piety. That simply could not be a less accurate depiction of them.
Pharisees apparently felt that defilement resulted from association with persons who did not observe the Law according to their view of it. In this they are very much like ISIS and other extremist groups who, if you dont believe and practice in the way they do, view you as a sinner worthy of destruction. They were quick to enforce the death penalty on people just as extremists do today.
Again, absolutely inaccurate, to the point of being offensively ignorant. It is, on the contrary, extraordinarily difficult to execute anyone under Rabbinic Law. During the end of the Second Temple period, they actually suspended capital hearings in the Sanhedrin altogether, since they could not be certain any convicted party would not be turned over to the Romans for execution, which was prohibited. A Sanhedrin at other times which executed someone once in seven years was called a "bloody court." Rabbi Akiva, the famous sage who was arguably the most influential of the early Rabbis, is noted for remarking that had he been on a capital Sanhedrin, no one would ever have been executed.
The Pharisees and Tannaim (their Rabbinic successors) were in absolutely no way comparable to ISIS. They were not radicals, and while they were certainly not always models of tolerance, they were not at all prone to simply condemning anyone who disagreed with them to death, or declaring them worthy of death. They dealt with different peoples in different ways, had more and less empathy for different groups, but were largely content to let be, if let alone.
Also the Pharisees (the name likely meaning 'Separated ones') were not of the priestly class
Pharisee comes from the Hebrew
Perushi, which more or less means "Those Who Interpret" or "Those Who Find Meanings." Nothing to do with separation.