EBKT has LOC-DME approach with 520ft minima, Schengen port of entry and reasonable train connections to Brussels (about 1:15) and is closest coming from the UK. No handling required if below 2T. GA friendly. Probably 15-20 minutes less flying time from the UK than EBCI and EBAW if that is important.
EBCI would have the lowest landing fees 12.10€ for <2T, don't know about parking fees, busy Ryanair airport, good ILS facilities.
EBAW has somewhat higher landing fees but is closer to Brussels and Antwerp is a major city too. Probably the quickest to Brussels. Airline flights into London City if needed. GA friendly.