EFC bonuses are broken and you need to take this into account when deckbuilding.

 EFC bonuses are a really interesting addition to the EFC deckbuilding challenge. Right now I think efc bonused cards are a must in every decks. That is right ! I would go as far as to say that +bonus should be taken into consideration when choosing the clans you want to play this week.

Regardless if you are fighting for top 1 or just looking to enter Z palace, they are a major help in reaching your goal.
-If you are fighting for top 1 every points count, so adding a bonus will help (Yunus talked about this in one of his public presets).
-If you are looking to enter Z palace, having a +bonus allows you to climb with a 50% winrate : let's say you only play against opponents without +bonus and you always have a +5 bonus. If you win once (+30) then looses once (-25) you end up with +5. Repeat this enough time and you will climb little by little.

So here is a begginer friendly review of the +bonus cards.
I will rate them : strong (please try them), interesting (they may not be the same, but they bring something special. It can be interesting to adapt your gameplan to what they bring in order to get the bonus), decent (if the stars align) and bad (you can play a bad +5 if you really play no other +bonus).

+bonus and the card level.
The lower the level of the card the better : to win the bonus points, you don't need the bonus cards to have a meaninful impact in the game. You can just old them and loose the game, as long as you win the game you are fine to win the points.
So 2* are extremly valuable. But bad 4/5 stars are a big no-no : they are your game winning cards. You don't want them to be shit.

This is the list of the cards that had bonus when the article was released (15/07), I sometimes review the cards that are added and removed from the list in my weekly post.
 

All stars

Jessie : decent. how time have passed. Now Jessie needs a bonus to be interesting to players. This is the definite proof that the power level of 2* have risen over the years.
So yeah, she is good. But definitly worst than Koran mail and not as good as Mulligan. And that is already two cards that shares the same flaws as Jessie.

Stenmark : intersting. yesterday I would have said she is bad, because I have a passionate distate to Courage cards, but I just realized one thing : regardless of what you build, you will always have to open two rounds of a game. Why not open those rounds with a card designed for it ?
She does lack damage, and winning a round with her may force you to win 3/4 rounds. But feel free to experiment with her. And with any other Courage cards ! and share your experience with them.

Banger
Shogunn : bad, too expensive.
Loocio : decent. Unlike Jessie, Loocio has never been particularly good. Like Jessie, Loocio suffers from increase power to the cards of his level. +5 is meaningful enough to warrent a try tho.

Berzerk
Roger : looks strong.
Flush : looks very intersting.

Dominion
Orka : bad, too expensive
Tyris flare : playing it right now, very good (mostly for his bonus carrying the card).

FPC
Chan : decent, like Jessie.
Sayura : interesing : yes she has low power and not that much attack manipulation. But 7 damages on a 3 stars is nothing to scoff at. Worth a shot.

Freaks
Olga Noel : decent to bad. She gets sniped by soa, sob and cancel power. So not sold on her.
Hula : intersting. Weaker version of Bikini joe ld. But looks fun to play. A 7/7 is threatening.

Frozn
Aaylah : Intersting/decent : if your deck lacks a first round opener.
Sah brinak : strong. Yunus is playing her.

Gheist
Zero dead : decent
Edmund : very intersting : unreductable 6 damages on a 2*. 

Ghost town
Ford : intersting (looks like a Charlie cr)
Chuck snow : very interesting. If your deck does not fear SOA.

Hives
Hal gladius : Intersting. worst Jessie against 2 and 3*. Better against 4/5*.
Neeck : power exchange huh ? Interesting, although a 4* that falls flat to many counters is a big risk.

Huracan
Derby queen : decent
El pina : idk, his stat are really shits. Unlike most other symmetries that are strong in Symetry and decent in asymettry. He is broken in Symmetry and a very lacking in asymettry.

Jungo
James : very intersting.
Odile : bad.

Junkz
Gibson : good ! Very good in a win 3/4 deck.
Dreen : Interesting (pss, this card can counter Dominions decently)

Komboka : cannot tell, I don't know the clan at all

La junta
Scooty : good if you have no good round 1 cards.
Trish : Very good ! She counters things like Dominions, Lom, Chang, Bmappe. And if you do not play against cards she counter she only costed 3 stars.

Montant
Mona cr : interesting ? or bad ? Yeah she is nice to cards with no power skills, but I did not find her that good when I played her last week.
Milovan : no, just no.

Nightmare
Oshitstune : what used to be the Nightmare flagbearer really felt out of favor... Still interesting. Especially against all those clans that count on their bonus to win the round.
Hubert : Intersting.

Paradox
Leonaparte : Intersting
Annunaki : Like trish it is a very intersting cards against the cards it counters. It also has a very intersting 2*.

Piranas
Rekved : interesting. But I am not sure if mono piranas is worth it.
Tyd : decent. If you go mono pirana you might as well include him.

Pussycats
Wanda : since her role is to be olded and loose the round, having a +2 bonus on top is very nice. Not sure if it worth to play her and Jayzel in the same deck.
Jayzel : very intersting ! Like Wanda, old her and enjoy the free points.

Raptors
Shaker : intersting.
Bartholomew : very good ! I played him in a mono raptor last week and really liked him !

Rescue
Lennard : intersting : since Linkos is very appreciated, Lennard I would give Lennard a shot.
Joana : She definitly is a cards that required to adapt your play to her. But it is worth doing so for her +5. And she still deals 5 damage plus can fix Rescue's lack of power.

Riots
Dinklage : very intersting.
Reeplay : intersting.

Roots
Amanie : good ! She is a slightly worst Methane who is frequently played in Gheist without any +bonus.
Delija : intersting.

Sakrohm
Cosmos : Very intersting, especially as a 3*
Slopsh : Just like Joanna, it is very interesting. 7 damages is nothing to scoff at

Sentinel
John : good, probably one of the reason Phil plays mono senty.
Dayton : bad.

Skeelz
Chiara cr : interesting.
Snowflake : very intersting. if you know how to play with swinggy cards that can either win or loose the whole game in one round.

Ulu watu
Dave : just like Jesse
George : Bad.

Uppers
Sean East : bad.
Djaya : bad. Not sure what you want her to counter. But 5 damage is not high enough for such a situational card.

Vortex
Dagg cr : Strong ! I would consider him even without the bonus.
Dreadlash : interesting.