Sujato, the most well known EBT enthusiast, has said that the Pāli suttas do take precedent. He argues this on the basis that the language (Pāli) is earlier and closer to the dialects the Buddha would have spoken in. He also argues it on the basis that the Pāli suttas are edited better, and that the language is tidier. He makes reference to the Dīpavaṃsa where the Theravādins claim that one of the issues with the Mahāsāṃghika school was how badly they kept their texts. They would mix up words, have plurals when there should be singular and so on. Sujato says that this is actually true. The Buddhist Hybrid Sanskrit that the Mahāsāṃghika texts are written in are a bit messy. Since the Theravādins prided themselves on being the school of textual study, the Pāli is preferable as it’s just in a better condition. He also argues that the Pāli takes precedent as its the only complete cannon that we have, only having partial bits from the other early schools.
I don’t know much about the kathāvatthu and perhaps we can study together the interesting points.
We can also gather a list of wrong views held by other sects, mainly the Sarvāstivāda and Dharmagupta which appear to be the chief root sects of the EBT texts.
The defining doctrine of the Sarvāstivāda tradition was that “all exists”, hence the name. By this they meant that all the dhammas exist in the three times and so the past, present and future all exist. This also means they were uncompromising realists, much more so than the Theravādins. For example, for the Theravādins the universal characteristics of dhammas have no sabhāva. They are an inference from the sabhāva-dhammas. For the Sarvāstivādins even arising, persiting, changing and ceasing have sabhāva and so are ultimately real. This was rejected by the Theravādins (and other schools) as it would lead to an infinite regression. The “arising of arising” and so on. On the temporal ontology, the reason why the Sarvāstivādins believed that the dhammas always exist was, in part due, to some of their sutras actually stating this but also because it was their answer to how kamma can operate in the present when the act itself has already ceased in the past. What we do now can have affects far into the future, because the kamma now always exists. The dhammas discharge their effects across time, and this is what we experience as momentariness, but the dhammas themselves never cease to be. In response the other non-Sarvāstivādin schools, which includes the group of schools known as the Vibhajjavādins but also the Mahāsāṃghika, argued that there is instead a “root conciousness” and it is this which explains how kamma can operate across lives. In Theravāda today, it is known as the Bhavaṅga. This was rejected by Sarvāstivādins, as they said this root conciousness cannot be found in the texts. Instead, the dhammas must always be. Liberation then for them was a process of “decoupling” from these eternal dhammas. This was also their answer to how we can remember the past. Since cognition has to take a real dhamma as an object, in order to cognise it, the past then has to exist for us to remember it. To say otherwise, that the past doesn’t exist yet we can remember it, is to claim there can be cognition of nothing. Indeed, this is actually the very criticism they have of Ācariya Moggaliputtatissa in their version of a Kathāvatthu. That he proposes “cognition of nothing”. It should be noted however that the Sarvāstivādins were not the only ones to adopt this tri-temporal realism. The Pudgalavādins also accepted it, and so were in a sense Sarvāstivādin too. What we commonly call Sarvāstivāda today is known as Vaibhāṣika, which is an orthodox form of the school based on the Abhidharma Mahāvibhāṣa Śāstra, which is a great commentary on their Abhidharma. Where the Pudgalavādins differ then is that they also accept the reality of the “person”. To them, the person is not the same as nor different from the aggregates. It isn’t an atta, but it’s a real concept. Interestingly, new research has shown that Venerable Nāgārjuna likely belonged to a sub-school of the Pudgalavāda tradition rather than the orthodox Sarvāstivāda-Vaibhāṣika school. On the Dharmaguptakas, whilst they did have some minor deviations from Theravāda doctrinally they were very close to it. So much so they could be called mainland Theravādins. The two schools certainly seemed to have shared a close relationship, at least early on. Of course eventually all of the Dharmaguptaka monks and nuns eventually adopted the Mahāyāna instead, which also happened to the Sarvāstivāda-Vaibhāṣika. Another early school that was very doctrinally close to Theravāda was the Mahīśāsaka (which is the tradition Venerable Asaṅga came from). They were so close in fact that Ācariya Buddhaghosa actually makes use of their version of the Peṭakopadesa in the Visuddhimagga. Historically the Mahīśāsaka were at one stage sharing the island of Sri Lanka with Theravāda, and it looks like over time they were simply absorbed into it.
On the EBT we have a version of the DN from the Dharmaguptakas. One MN from the Sarvāstivādins. Two SNs, one from the Sarvāstivādins and one from the Mahīśāsaka and one AN from the Mahāsāṃghika school as well as random sutras from unknown traditions. In terms of the various Abhidharmas we have a complete collection of the Sarvāstivāda-Vaibhāṣika texts, a complete version of the Dharmaguptaka Abhidharma (the Śāriputrābhidharma) and only bits of the Pudgalavāda Abhidharma.