You can give mine a try if you want, I had to tone it down alot because of people crying about it. I can solo it on my Kat/Regen and my Dark/Rad, but they are pretty IO'd out.
Deadly Sins! - 99366
I think I am going to buff it back up soon, the ally in the last two missions is pretty mean, he will let you solo the AV at the end if you want.
Mito: We're providing feedback on everything we run, with the exception of cases where we try something with random people and find that we're actually going to need a coordinated team.. and even that's just delayed. If youre seeing plays of your arcs with no feedback, someone else is playing them 
My arc 53420 has a mission that can be quite difficult. One of the missions has a boss that is near impossible to solo. I've balanced it by making sure there are enough allies sprinkled across the map such that a solo defender could do it by collecting the various allies.
You can up the challenge by refusing to rescue any/some of the on map allies and take on the big boss by yourself or just your group.
The boss was benchmarked against Black Scorpion, Ghost Widow and Lord Recluse, and fits right in between GW and LR for difficulty.
Storywise, the arc is directed toward a post-patron arc villain, preferably 50. It has been finished on all challenge levels as well.
PS. Just remember that many (if not all) missions should auto sk/exemp for mission architect, and that post 35 groups can gather in RWZ so you can co-op the story arcs as well.
I have a mission arc ID: 139767
The Demonatrix & The Mad Creepers (2 diff custom groups)
people just want a ton o' tickets without a challege.
No dual blade losers in this arc. lol have fun.
All 3 of my arcs in my sig feature a custom villain SG and the middle arc has a custom group that I have been told is a challenge. And if thats not enough of a challenge the final mission has a non-required AV... Dr.Apocalypse (NRG Blast/Will) BWAHAHA!
From testing you will have to put it to max challenge level to get the AVs and EBs to spawn hard enough.
My 50s:
Prime Minister MA/SR Scrap - Protector
Captain Hit-Guy DM/Reg Scrap - Freedom
Prime-Minister ILL/TA Troller - Freedom
Ultimate Minister Inv/SS Tanker - Freedom
I'd like to add 91887 and 50715 to this list.
I wanted to bump this back up. I like playing the more challenging arcs. Anyone have more?
I designed an arc that was meant to be very challenging. It's in my sig. I'd love to hear your feedback on it.
Arc 185502: Who Killed Snow Globe? a mini mystery Put together the clues to solve the case!
Arc 22832: And Hell Hath No Fury (extreme)
Will you be the key to the Knives of Artemis' survival? or the instrument of their destruction?
It's really just a single battle vs. the Honoree, but if this is your idea of fun (that's one player at Challenge Level 1), you could try this one:
Arc ID # 158569
The mission was meant to just be an intro to a longer arc (which I need a better story for and is just languishing currently) where you just click a single glowie and everything else is just "for show", so I deliberately made the Honoree with as many of the ugliest ambushes I could, intending it to be unsurvivable at AV level.
CoH Codex : Demo Models/FX/MOVs : Demo Info
Arc 111022: "Doctor Geist and the Scientific Method"
If you are looking for a challenge, I would definately like to recommend mine. I've had to tune it back a bit because everyone was telling me it was TOO hard.
A bit about it:
Name: Rise of the Tech Ninjas
Arc ID: 18440
-It is a 3 part STORY arc(not just abunch of mish's) : )
-It is entirely made up of custom creatures(I believe 12 different types), including EB's (No AV's)
-Originally, all custom creatures were */ninjitsu stalker class.
That's the part I had to change, having 5-6 minions AS you
really sucks. All minions and most LT's are now */SR
Other than that, please try it out and let me know what you think. Having an AoE blaster on the team is a definite plus to bring the little guys out of hiding.
(I have an Ice/Ice blaster as my main on Infinity "Iceshot")
So hey all.....
Looks like a few of you ran my arcs...thanks for the stars and all, but I would LOVE some feed back! Please tell me what you ran it on, difficulty and notes. As of now I will be using this thread as suggestions for arcs to play from like minded forum people, hope you all do the same
What I am looking for is challenge and story, balance those two and I am five star gold! AND I promise follow up in the form of feedback. Sunday I will put some time in (I work weekends) so lay it on!