Another vote for UTMB, or the 60m I managed at least, the French/Italians don't seem so bothered about the health regs we have so you get bits of sausage, salami, cheese at the CP amongst other things you might expect. Crowd support and big event feel. The route is just amazing, the climbs massive, having a go at the TDS this year, which looks to be equally promising.
It's a tough call in blighty, I've never said "never again" to any event over marathon distance. Lakeland 50/100 is good for similar reasons to UTMB, route and CP nearly as good as UTMB. The Calderdale Hike of 2009-11 is another favourite. Support, CP, friendly feel were as good this year, but slightly prefer previous route. But the Fellsman is probably my favourite UK event, great challenging often off-trail route peak-bagging in the Yorks dales and you get a menu in the event info booklet of the great variety of CP food!
Hmmm... food on offer seems to play a large part in my favourite events 