Kilian already announced he's racing UTMB this year so he and Jim will be squaring off. However, I'd call Francois D'Haene the favorite right now based on his recent performances. We've yet to see what Jim is capable of on the real Euro scene. It's whole different game.
UTMB this year will be the most stacked file in ultra running history.
Dylan Bowman (USA) – 2nd 2015 TNF 50 Mile, 4th 2016 Lake Sonoma 50 Mile
Jeff Browning (USA) – 3rd 2016 Western States 100, 4th 2016 Hardrock 100
Sébastien Camus (France) -2nd 2015 Grand Raid Réunion, 7th 2016 UTMB
Sage Canaday (USA) – 3rd 2016 Transvulcania, 11th 2016 Western States 100
Pau Capell (Spain) – Winner 2016 TDS, 11th 2016 IAU Trail World Championships
Tòfol Castanyer (Spain) – 2nd 2014 UTMB, 8th 2016 IAU Trail World Championships
Julien Chorier (France) – 6th 2015 Western States 100, 8th 2016 UTMB
François D’haene (France) – Winner 2012 and 2014 UTMB; winner 2013, 2014, and 2016 Grand Raid Réunion
Yeray Durán (Spain) – 2nd 2016 TDS, 14th 2016 IAU Trail World Championships
Jordi Gamito (Spain) – 6th 2015Grand Raid Réunion, 5th 2016 UTMB
Gediminas Grinius (Lithuania) – Winner 2015 Ultra-Trail Mt. Fuji, 2nd 2016 UTMB
Miguel Heras (Spain) – 2nd 2013 UTMB, winner 2016 Ultra Pirineu
Didrik Hermansen (Norway) – Winner 2016 Transgrancanaria, 2nd 2016 Western States 100
Luis Alberto Hernando (Spain) – 2nd 2015 UTMB, winner 2016 IAU Trail World Championships
Kilian Jornet (Spain) – 3-time Hardrock 100 winner, 3-time UTMB winner
David Laney (USA) – 3rd and 4th, respectively, at 2015 and 2016 UTMB
Andrew Miller (USA) – Winner 2015 Bighorn 100 Mile, winner 2016 Western States 100
Giulio Ornati (Italy) – 5th 2014 CCC, 9th 2016 UTMB
Diego Pazos (Switzerland) – 4th 2015 Grand Raid Réunion, 6th 2016 IAU Trail World Championships
Andy Symonds (UK but lives in France) – 4th 2016 Transvulcania, 9th 2016 IAU Trail World Championships
Xavier Thévenard (France) – Winner 2010 CCC, winner 2014 TDS, winner 2013 and 2015 UTMB
Tim Tollefson (USA) – 2nd 2015 CCC, 3rd 2016 UTMB
Jim Walmsley (USA) – Winner 2016 Lake Sonoma 50 Mile, winner 2016 JFK 50 Mile