I've worked with Monumetric for the past four months getting the ads set up on my site, and I couldn't be more impressed with their team. You aren't just a number to them, they clearly care about your success and the success of your site. And they put in the work to prove it.
They will, of course, make recommendations that they think will maximize your revenue, but I found them to be very responsive to my desire to minimize the impact of the ads on my readers' enjoyment of my content. They will work with you to customize your layout at a very personal level. They have great communication, and got back to me right away with responses to all my questions and concerns, even though I am far from a top earner when it comes to ads or traffic.
It's clear that they believe in what they are doing, and that they want to be a true partner, acting in your best interest, as you navigate the world of corporate ads. And on top of that, I found their technical expertise in terms of tackling new challenges to be exceptional. (For example, I wanted ads hidden for my Patrons, and their engineering team worked with me to make that happen quickly and smoothly.)
While there are no guarantees of fortune when it comes to ads—that will depend of your traffic and how your readers interact with your site—if you have any hesitancy about whether these folks are trustworthy and the right people to work with, my experience has been that they are among the best of the best of any company I've worked with.
Don't hesitate. If you want help with your ads, this is the right team.