hi , i would like to make some duo with a bard and play in FG and i cant decide between the both class. Champion looks to have more tools than hero but i dont see a lot of them on uthgard excepted solo and its not my aim. So could you help me to make a choise pls ? Advantages and drawbacks tell me everything thx

Do a BM Det, Charge, Slam if u spec it. Much better in Duos and best chance to get a slot in FG.

Uhm the matter here is wether we want to take old RAs in account or not, because that's what I did in posts like these for the past 10 months. I discouraged playing a lot of classes because of the "incoming" changes. Champion was one of them.

With old RAs it's really simple, avoid Champions. Not having anymore determination (the CC reducing RA) will make him useless in group fights. You will be a beast in 1v1 but since that's not what you're looking for, just don't bother.

Speaking of current RAs it isn't that straight forward. Heroes are more popular for a few reasons. Most importantly they have stoicism which adds another 25% CC reduction, a distinct advantage hybrids like Champs don't have. Also they can spec some nice defensive group RAs like Soldier's Barricade or Dashing Defense whereas the best RA on Champs (Static Tempest) is bugged here.
When it comes to the defensive role Hero is probably slightly better. On the one hand a Champ has a haste debuff, which isn't that shabby, and a cast snare which is really useful. However a Hero can obtain a behind snare with 6 points in Spear without giving up his LW line giving him access to three snares (frontal LW snare, blades/pierce side snare and LW frontal snare). What makes a Hero better for deffing in my eyes is Stoicism, so there's less chance of your team getting shred apart while you're CCed. Apart from that Hero has the RAs I mentioned above which are usefull if you play the def role (though I myself prefer dmg RAs).
In a more offensive role I would tie them. Hero obviously once again has the advantage of more CC reduction but a Champ's spells bring him a noteworthy advantage if you know how to use them.The majority of champs here just faceroll their Qbar on one target which is ofcourse dumb. However the main issue here is that they're both outperformed by a BM because it suffers less from the high blockrate. Attacking a class with a shield with an LW is frustrating. Apparently the blockrate was lowered though recently but I haven't played with it yet so not too sure on this.

Anyway you can't go wrong with a Hero. It's easier to play, more popular in groups because of Stoic, has good RAs and a nice array of weapon styles he pick from .
In the hands of most people a Champion is probably worse but if you can master when to use your spells he is for sure worthy of a place in a group.

If you wanna run FG pick Hero or BM.
If you wanna run small men pick Champ or BM, Fian has too little utility in small men imo.