As Salamu Alaikum, I will tell you the best way out of this fitnah. I've faced major problems because of this name callings amongst the Ahla Sunnah.
First of all, try to avoid completely the ones whom are called Salafi/Wahhabi. They refer to the same people, and their main thing is not to follow a madhab. However, this not following of any of the 4 madhabs brought together other major problems with them. They basically say that, anyone has the ability to be a mujtahid if they only study the sahih hadith and Qur'an, which is stupid. Occasionally, they will call followers of a madhab and the sufis mushrik, kafir etc. Their aqida is also mainly that of the athari, which is not really recognized as the aqida of the Ahla Sunnah. They don't interpret things about Allah(cc) at all, for example. They believe that Allah(cc) is sitting on top of the throne(arsh), they believe that Allah(cc) has hands etc. They are devoid of common sense. And following them can distrup your own aqidah. Don't listen to their self-proclaimed Mujtahids fatwas also. Like Zakir Naik, Bilal Phillips etc. Their fatwas aren't trustworthy as they are basically self educated. They have really bad manners about the Prophet(saw) as well. They say that he(saw) is dead, no benefit comes from him, making dua through him, such as "Allah, grant me such an such for the sake of your Prophet(saw)" is SHIRK. They say that, if you make dua like I mentioned, that is shirk. This is clearly against the traditional belief of the Ahla Sunnah. This much should suffice about them.
The Deobandis and Barelvis are a weird case. Deobandis are basically followers of the scholars from Darul Uloom Deoband, which has produces some of the greatest scholars recently. The Barelvis are the followers of Ahmad Rada Khan, which was a great scholar as well. The Deobandis and Barelvis are both from the Ahla Sunnah, and they are both mainstream sufis. The main difference with them is that, the deobandis don't praise the Prophet(saw) as much as the Barelvis do, the rest of the problems they have are pride issues. The Deobandis say that the Prophet(saw) was the perfect man (insan-i kamil). And they don't really want to comment on it any further. The Barelvis say that, as in accordance with the traditional belief of the Ahla Sunnah, that you can praise the Prophet(saw) as much as possible without making him divine. (For more about this issue about the status of the Prophet(saw), you can read Imam Tahawi's book on aqida about our Prophet(saw)). They have other issue as well, but not that important. The best is to avoid the arguments between the two groups as this brings much doubt to the mind. They are both trustworthy, and their publications can be read without damaging your aqidah. However, this is a generalisation, some of the scholars amongst each group can be corrupt, messed up etc. I don't know every single one of their scholars, but in general they are trustworthy. But as I've said, avoid their arguments, this makes the shayatin very happy as it just causes fitnah and nothing else.