They scored 38% and 45% respectively with their customers, while Sky (48%) and EE (49%) came close behind them in the Which? survey of 1,800 people, reports The BBC.
Frequent price rises, connections that drop, unreliable speeds and “woeful” customer service all contributed to the scores, the consumer group said.
The four account for almost three-quarters of the UK broadband market.
BT alone accounts for almost a third of the country’s broadband connections.
Zen Internet had the highest customer rating at 86% in the survey, followed by Utility Warehouse (81%), John Lewis Broadband (68%), SSE (66%) and Plusnet (65%)
Virgin Media (52%), Vodafone (50%) and the Post Office (48%) were also included.
Which? surveyed people about their broadband in November and December. The customer score is based on satisfaction levels with their provider and whether they would recommend it to others.
Those surveyed were also asked to evaluate aspects of the service, with five stars being the highest rating in seven categories, including speed, reliability and customer service.
BT scored just two stars in all seven categories, while TalkTalk also scored two stars in each except value for money, for which it got three stars.
Just four of the 12 providers scored more than three stars for speed: Zen Internet, Utility Warehouse, Virgin Media and Vodafone.
Alex Neill, Which? managing director of home services, said: “The big players still have a long way to go to satisfy their customers, so if you’re unhappy with your broadband, complain and look to switch if your service doesn’t improve.”
A BT spokesperson said it was disappointed with the survey result and apologised to any customers who had been let down.
“Generally, our broadband performs extremely well for customers and offers very reliable speeds at peak times, according to the latest Ofcom broadband speeds report.”
A TalkTalk spokesperson said: “Our extensive improvement programme has already led to fewer faults, faster average speeds, shorter times to resolve issues and customers reporting higher satisfaction levels.”