Hi.
Orp are NOT the easiest to push over and I've raised well over a hundred birds.
I would NOT go with all orps... IMO they are too heavy bodied for the amount of eggs they put out and NOT nearly as "friendly" as people claim... in addition to the broody beeothces!
My TRUE opinion... yes, some breeds have a certain reputation. But ALL birds are individuals. I have ran a mixed flock for a while and even Orp and Silkies *can* be bullies!
Get what you want! In my opinion, and experience... a rainbow nation IS the way to go.

You get a variety eye candy on pasture which my neighbors all love. You get to try different breeds. And I feel like a kid everyday when I go collect eggs and see what the basket holds. It also makes it easy to notice if something is wrong with an individual and make it easier to keep track of which one might need help. It helps to combat everyone molting at the same time as well and to know who is or isn't laying.
I suggest getting 3 this year and adding two more next year that won't molt when this years 3 do and you will still have eggs through winter.
My starter flock was a Rhode Island Red, an Easter Egger, and a Barred rock. Even after a ton of birds and different breeds... I will probably ALWAYS have a rock and an EE in my flock... just for personality. Only thing is... among the breeds, still all are individuals. The skittishness really is about confidence. So when you pick out chicks, pick the ones that aren't hiding in the back... being aware that SOMETIMES the confidence is an indicator of mistaken gender identification. Personality totally breeds forward. I have had skittish and confident in most of my breeds, EVEN from the same batch.
What I will suggest... don't get one white bird if all your others are black or vice versa. And also don't add like a crested polish on with all non crested as that does SOMETIMES invite picking. Truth is there are not MANY hard fast rules in chicken keeping. ONLY 2 that I know of so far... roosters don't lay eggs and females don't grow pointy saddle feathers. Everything else... seems to have exceptions... Hens can crow and even grow spurs, though it isn't super common. And I've totally seen a rooster sing the egg song.
A couple breed comparison charts for your consideration...
http://www.sagehenfarmlodi.com/chooks/chooks.html
https://livestockconservancy.org/images/uploads/docs/pickachicken.pdf
Hope this is helpful!
One last thing... get a second opinion on ANYTHING you are told by a feed store employee. They are often well meaning but with little to NO animal experience of their own, and WAY too often giving REALLY bad suggestions.

For example... you DON'T need a 250W heat lamp for 3 chicks inside a home... that is the standard for the industry where they are raising hundreds of chicks in outdoor barns. So what's right for one person may or may NOT be right for you.

I like lower wattage non light emitting bulbs that allow my chicks to sleep through the night as they would if they were under mum. The temp they say to keep chicks at... is the temp it should be directly under your heat source (I tried mama heating pad, and it ain't my style). But chicks should still be able to access cooler regions to eat, drink, and play... while just popping back under the heat to warm up and sleep.
Best wishes on your chicken adventures!