There are 8 internet providers currently available Coimbatore including BSNL and Railwire. tikona and air India are good for unlimited plans also check List of broadband connection in Coimbatore.
Tikona broadband offers many flexible plans to choose from, it has unlimited plans with FUP limit starts from 512kpbs to 10MBPS pricing starts from Rs 675 to Rs 1250 per month and installation charges are Rs 750 and installation charges are waived off if you subscribe for 6 months or more.
Air connect india has very good tariff plans for high speed starts from 10mbps to 30mbps post switch to 2mbps price starts from Rs599 to Rs1599.
Raliance broadband offers 4 unlimited plans starting from 1mbps speed at Rs 599 to 4mbps at Rs 1099. Thunder 899 plan offers 4mpbs speed upto 20GB at Rs 899 post speed switch to 1mbps, this plans is good for people looking for less usage at high speed.
Airtel offers unlimited plans starting at Rs799 to Rs2399 per month for fastest users with speed starts from 2mbps to 16mbps post all plans switch to 512kbps.
conclusion : If you are looking for high speed plans then go for air connect india and if you are looking for cheap broadband plans then tikona is best.