Antwerp (ANR) could be considered to be a similar airport to Ostend, the difference being that it can't handle jets. It can only support flights to Manchester and London City.
I've flown in and out of Antwerp on Sabena 737s.
(and Dakotas, F27s, Convair 440s, Heralds ...)
Natural advantages: I have walked to the city centre in 30 minutes.
Natural disadvantages: I have driven - at legal speeds - from Zaventem to Antwerp Airport in 35 minutes. The direct rail link from Zaventem to Antwerp city is just about complete.
A similar airport to Ostend would be Manston.