Brussels
I travel from Bournemouth to Brussels at least once/month. My options are usually Flybe, BA from LHR and Eurostar.
I flew Flybe last Monday, there were fewer than twenty pax and it was expensive (Flybe is usually pricey for any day/time/route that suits business). The Brussels flight times from SOU are generally not very convenient, dont get you into down town Bru before about 14:30 local, by which time most of the business day is gone, and you have to pay a crazy price to get the business lounge thrown in at SOU - it doesnt come as standard with the flybe frequent flyer which is a mistake when compared to the competition.
Eurostar tickets are usually outrageously priced often more than 300 euro one way. But its comfortable and fast, and almost always full and the seats are big enough for working.
More often than not I fly from LHR, on BA. Its usually less than half Eurostar price, has a good dep time for business in BRU, is always full. And BA has a decent lounge in T5, where the breakfast is good, the papers and magazines are free, and the delays are no worse than the Flybe record.