Normally Bhagat Baani, Bhatt Baani and Salok Sehaskriti are the hardest to read for a new Paathi. Second hardest after the aforementioned Baanis are the 22 Vaars. If one can get fluent in Bhagat Baani, Bhatt Baani, Salok Sehaskriti and 22 Vaars, then one covers pretty much 1/3rd of total Baani. The rest of the Baani is comparatively easer to do Paath.
With the exception of perhaps Bhagat Baani in Raag Soohi, it is quite easy - on par with Raag Bilaval and Raag Sorath. Out of Raags, I have found Raag Saarang to be one of the hardest. Professor Udai Singh, who has done Sangat of Bhai Sahib Randhir Singh jee, once mentioned that his favourite Raag is Raag Saarang and he passionately said that in Raag Saarang Vaheguru is Pratakh. Another Singh who is a good Paathi once mentioned that his favourite Raag is Raag Tukhaari. He loves to do Raul there.
My favourite Baanis to do Raul in Siri Akhand Paath Sahib are from Salok Sehaskriti to Bhatt Baani. I just LOVE Bhatt Savaiye. Other than that, the Baanis that I find extremely uplifting are Shabads of Mahalla 5 in Raag Sorath, Raag Bilaval and Raag Bhairon. I feel that if one is sick or is in some trouble, these Baanis really rejuvenate one; so much so that even a dead person can rise, if it can listen to these Baanis.
Having said that, the 7 Shabads of Mahalla 4 in Raag Maajh are just fabulously full of Bairaag. These Shabad are followed by just amazing Shabads of Mahalla 5 starting with Mera Mann Lochai Gur Darshan Taayee||. Each and every Shabad is of greatest height. What should one say in praise of these Shabads. Just read them to know what Daas means.
Then the Ashtpadis of Siri Guru Amardaas jee in Raag Maajh are just pure bliss. These Ashtpadis are rivalled only by the Maaroo Solhe of Mahalla 1 and Mahalla 3 in Raag Maaroo. If one reads the Ashtpadis of Mahalla 3 in Raag Maajh in one sitting or reads all Maaroo Solhe from Mahalla 1 to Mahalla 5 (there are no Solhe of Mahalla 2 and Mahalla 3), one finds that one's mind becomes still like an ocean. The effect is very similar to doing a concentrated Paath of Siri Sukhmani Sahib. Naam goes on effortlessly then.
Out of the Vaars, the Vaar Maaroo Dakhne is just Alaukik (out of this world). The language used is Lehindi Punjabi and the style is so raw, so blunt and so full of innocent love that the Paathi does not know how to sustain the Anand and emotions ensuing from it. Vaar Maaroo Dakhne is probably the hardest of the Vaars or at least in the same range of difficulty as Maajh kee Vaar or Malaar kee Vaar of Saarang kee Vaar or Jaitsree kee Vaar, but it is also the most Anand-giving Vaar. Then Asa kee Vaar is there to sing along with the Chhants of Mahalla 4. What is there in the world that can match the Anand of Kirtan of Siri Asa kee Vaar?
Out of Ashtpadis, other than Mahalla 3 Ashtpadis in Raag Maajh, the Ashtpadis of Mahalla 4 in Raags Bilaaval, Nat Narayan, Kalyaan and Kaanra, which constitute Siri Sukhmana Sahib, are packed with love and Bairaag for Darshan and Naam. Two Ashtpadis of Siri Guru Nanak Dev jee in Raag Aasa, and the ones that are also called Babar Baani, are very informative and are of historical value. Reading these Ashtpadis one gets the feeling of temporary nature of this world. Nothing is eternal here. All is just an illusion, it seems like.
Out of Chhants, my favourite are the 6 Chhants of Mahalla 4 in Raag Bihaagra. The following 9 Chhants of Mahalla 5 too are just amazing.
What should one say about Gurbani. The whole of Gurbani is just Amrit. When drinking a cup of Sharbat, can one tell which part of the cup has more sweetness and which has less? Same way, Gurbani is just full of Amrit, all over; we like certain Gurbani more because of our different Avastha and different language background and upbringing. As an example, Maaroo Dakhne may not have the same effect on someone who does not understand Lehindi Punjabi but one who can understand it, has Vismaadi effect. Same is true for Salok Sehaskriti; they are hard to read and understand but there is a lot of Rass if you understand them and pronounce them correctly.