I can see the benefits of both SEN and STN
BFS to SEN has not worked due to the difficulty of getting tomSEN for the 7.15 flight therefore poor LF. The daily flight is geared to suit the BFS pax, morning departure on Mon and Tues with late evening returns on Wed , Thurs and Fri etc
STN is still very popular with the NI pax, and I recently flew BFS to STN and the flight was full both ways.
SEN /BFS can only work double daily if aircraft is BFS based and maybe operated as a through flight to European destination (now that would be something for EZY to consider)
Both airports are good but I feel EZY should be looking at connections as well, recently flew back LYN, STN to BFS. Don't think SEN has that many.
Many pax use FR as they have good connections at STN, EZY should be looking at the same. Not all of us live in London, Birmingham or other large populated areas and have to use London for connections