FlyerTalk Evangelist
Join Date: Aug 2011
Location: Barcelona, London, on a plane
Programs: BA Silver, TK E+, AA PP, Hyatt Globalist, Marriott LT Plat, Hilton Diamond
Posts: 13,053
Be aware that flights 2-4 arrive at a different terminal, so you'll have to take the bus to T4 for IB check-in.
To avoid delays, you will want the flight option with the highest probability of the airplane physically being at LGW, so that delays aren't built up over the day. i.e. even if the weather is fine at LGW, if the airplane is coming in from elsewhere you might still have weather delay issues.
Air Europa will be a MAD-based plane I presume, so you'd have to trust that the plane also leaves MAD on schedule and doesn't run into air traffic restrictions coming into LON. I would definitely avoid Norwegian since surely there will be a flight or two squeezed into the morning for that airplane.
The Easyjet plane would probably have been sat overnight at LGW, in which case it's the likeliest to get out in the morning relatively promptly.