As far as LGW-VLC is concerned, easyJet should do well; despite BA commencing flights on this route, easyJet will, I expect, offer better fares.
Well that doesnt matter anymore as British Airways has announced that it is not starting its Valenica and Porto routes from Gatwick due to the difficult trading conditions so easyjet as far as i know will be the only operator on the routes. So i suppose the prices now maybe higher as they wont need to have competitive prices with BA.