Try bikarnerwala's jalebi at Gurudwara road ,Karol Bagh . Their kesar jalebis are the best .
I personally find Old Famous Jalebi Wala HIGHLY OVERRATED in Old Delhi. Try Om sweets in Hari Nagar
Imly Also serves jalebi with rabri . must try
Visit chandni Chowk you will find lots of jalebi shop.. Specialy pandit jalebi vala with rabri. 50 Rs per jalebi nd 25 rs rabri. This shop near seshganj gurdwara.
Kanwarji's at the corner of Parathey Wali Gali is also a good option if you are looking for crisper variety.
The most popular place for jalebis is in Dariba Kalan (Chandni chowk) which is Old famous Jalebi wala (almost 130 years old) Another is Senor Dhan Singh in Yusuf Sarai Market. It has got really juicy jalebis. You can also try the iconic Mawa Jalebi at Sultan Ji at Matia Mahal Bazar, Jama masjid