It's a shame because a few years ago I'd agree but I don't miss them one bit nowadays. In my view they have increasing demonstrated their lack of vision when it comes to routes and scheduling decisions, as was the case the entire time they were at EMA. That company makes quite clear they have more commitment to certain airports than others, letting smaller bases suffer at the expense of larger ones. Like they did in the past, they won't give EMA the commitment it deserves.
I know there will be some who won't agree as they are already the dominant airline, but I think FR would be the best. I think EMA's biggest problem isn't the amount of airlines but the range of routes it serves. As Balair says it's become far too dominated by the leisure market. If it were LS it would probably be more ALC, PMI, TFS... same old boring stuff.
FR I think would have more prospect of flying a better mix of routes (as they currently do) with cities as well as the bucket and spade market. Possible gaps I see for FR are places like Bologna, Lisbon, Oslo, Vilnius or bringing back Bratislava or Marrakech for example.