Choosing best service centre is a relative stuff. Take any service centre of any brand, there will be some positive and some negative feedbacks about it. It also depends on the particular engineer working on your issue.
If you’re looking for a service centre in Hyderabad, you can look for it at the company website

best LG air conditioner service center in Hyderabad

1. SIDDI VINAYAKA ENTERPRISES Plot no : 89,Venkateswara Enclave Jeedimetla,Qutbullarpur Village Phone : 8297299997,7702202152
2. 2HYDERABAD DIRECT SERVICE Plot NO 38 Nagarjuna Hills, Punjagutta Phone : 9985487556
3. 3TAJ AIRCONDITIONING 1-2-524,Gagan Mahal Himayatnagar Phone : 9490441114,9908776775
4. 4SRINIKHIL AIRCONDITIONERS Shop No 13, Global Enclave Bssspencer’s Market Phone : 9866247644,9652696472
5. 5SRINIVAS ELECTRONICS-ASC Flat No:106, Kamal Prasanna Nagar Colony, Phone : 9985308090,9032300032
6. 6VAISHNAVI COOL SERVICES H.No:12-13-677/88, Plot No:165, Kimti Colony, Tarnaka Tarnaka Phone : 9948573304,9100968741
7. 7COMFORT COOL SYSTEMS 3/9, Ramdas Garden, West Mardepelly, Secundrabad Phone : 9849990679,9581226679
8. 8SRI RAMA ENTERPRISES #2-2-1164/27/A, Street No:18 Tilaknagar, New Nallakunta Phone : 9701157777
9. 9S P ASSOCIATES H No. 12-2-822/B/2/AB, Ayodhya Nagar Colony, Near Pillar NO:28, Mehadipatnam Phone : 9177769532,9542555541
10. 10HYDERABAD DIRECT SERVICE 2 1-4-53/1,#39,Vasanth vihar colony, Habsiguda, Phone : 9989725033
11. 11SRINIVASA SERVICES 11-163, Plot No:81, Sowbhagya Puram Dilsukhnagar, Phone : 9030374455
12. 12SREE TECHNO SERVICES PLOT NO:270 & 230, SHIVA NAGAR COLONY, HYDERGUDA PILLER 154, RAJENDER NAGAR, ATTAPUR, HYDERABAD HYDERGUDA, ATTAPUR, HYDERABAD Phone : 8885085768

Source: Official LG India website