Would not bother with J if your flight is a short hop from one European country to another. Basically Tap's J seat is a Y seat with the middle seat left vacant. The service on TAP is generally very poor and they are always late. You will never complain about Ek again after stepping onto a TAP flight. Better off using easyjet for European hops. Long haul, TAP does not have a good record either, just read Skytrax to get a flavour of what to expect.