For Carnatic Veena, which really is the gold standard of being able to render vocal composition on a stringed instrument, there are lots of excellent artists, but S. Balachander is really the connoisseur’s choice. He began learning sitar at a young age but decided that the instrument wasn’t capable of rendering rāga ālāpana the way he wanted, and switched to the South Indian Veena and revolutionized the way it’s played. There’s a good book by Vikram Sampath about him. A more popular modern Veena performer is E. Gayathri and the absolutely astounding young man Ramana Balachandhran, who is a bit like a Mozart on Veena. 

This is an excellent book on the 72 Melakarta ragas with western notation included and brief explanation for each. It goes without saying, of course, that the precise performance of the ragas and the gamakas involved in each has to be learned by listening and oral tradition. 

This might have been mentioned in the preceding chain, but https://www.karnatik.com is one of the oldest online resources for our music and has grown quite a bit over the years. I’d use it often for finding the sahitya for various kritis and also for the Hindustani - Carnatic Raga conversion table. While the Carnatic melakarta system is older and traces Ragas to the 72 foundational scales, Hindustani’s 10 thaat ragas were set in the early 20th century by Bhatkande who wanted a distinct but similarly standardized system of raga classification. His system became the standard for north Indian music as it is taught in Indian Universities. Here too, there is some cross-pollination of ragas, though they change names, and some ragas are much more popular in Carnatic or Hindustani repertoires, and thus are played in that style even when performed in a classical Carnatic concert. So for example, Raga Bihāg is way more popular in Hindustani music, so when it is performed in Carnatic concerts, the gamaka and sancāra (rāga exploration) maintains the Hindustani style. All Indian instrumental music originated from attempting to mimic the singer’s voice, so the lyrics for compositions are almost always written by various Bhakti tradition poets. This even when rendering the composition on an instrument, the musician must know the lyrics and articulate the phrasing of the notes to pronounce the words of the song. While Hindustāni music’s gat compositions often don’t have lyrics, Carnatic compositions always have lyrical portions. 

Lastly, there’s the book called the “Grammar of Carnatic Music” by K.G. Vijayakrishnan which is theoretically dense but I really appreciate because it’s really important for thinking about how grouping notes into phrases that not only are accurate for the raga being performed, but is meaningfully arranged. Over the years, musicologists have compared the raga system to jazz and Blues scales, and there have been lots of really great collabs, but all Indian musicologists and scholars will tell you, rightly so, that the rāga is distinct from a musical scale or mode because of the importance of microtones (the accepted number of these differs between theoreticians and was subject to great debate for centuries) and movements between notes.

Aside from that, it’s interesting to note that the violin’s adoption in south India around the early 19th century by Bālaswāmi Dikshitar (brother of famous Carnatic composer Muthuswami Dikshitar) came around the same time that the British were trying to criminalize the tawaif system and thus labeled sārangi players disreputable since they were often low caste (despite being prodigious musicians). So the adoption of the violin for Carnatic music to do essentially the same thing as the sārangi, that is accompany a vocalist in concert, seems to have been a purposeful choice by the Brahmin Dīkshitar. Unlike the other early Carnatic composers like Purandara Dāsa and Tyāgarāja who wrote in Kannada and Telugu, respectively, Dīkshitar wrote almost exclusively in Sanskrit. Dīkshitar’s choice flew in the face of the the entire point of these earlier Bhakti tradition composers who were pushing back against Brahmanical orthodoxy and their discriminatory rules and practices by making the knowledge in the Sanskrit texts available to non-elites through colloquial languages. As we see so often, even in Indian music, we can’t escape the Brahminization of practices that began in protest against them.