Irrespective of free to paid or paid to paid (LTF needs effort to switch)..
condition: as long as you fulfil the requirement and not aim for super-premium / high level card in that bank
- Citi ( as long as limit sufficient, through call )
- Axis ( through chat or phone banking )
- StanC ( like CIti easy as long as limit sufficient, through call )
- AU ( based on limit, through email )
- Indus ( based on limit, and ok with joining fee through email )
- Kotak ( through app )
- BOB ( if you fulfil income then easy from premier to eterna also, otherwise any card through email )
- ICICI ( if you ok with paid, through twitter or phone )
- HDFC ( based on spends, income and not for super-premium cards )
experience may vary from person to person, so check all and cumulatively update from easy to hard.