I have to chime in my 2 cents. Last year, I started a thread and asked the same question, but the only difference was I am single so the care, walking, everything is down to me…everyone basically said, 2 are better than 1 and the single folks wrote in that basically the only problem might be bringing 2 dogs to friends when you go to visit.
Anyway, I added Brando in March...best thing I ever did! In my case, both Brando and Ruby are retired show dogs. Both Brando & Ruby are 3yo. My breeder found the perfect match for Ruby. Crazy high energy...very playful and fun...both of them. Ruby and Brando constantly do the B500 inside & outside. In fact, on the weekend I've seen them go at for over an hour :D.
One thing that is way easier if you have 2...the bathroom habits. When one goes, the other nearly always goes immediately after. Walking can sometimes be a bit of a challenge still as I'm still getting used to walking 2 at the same time, but generally it goes really well.
During the day when I'm home, Ruby and Brando sometime curl up together...mostly happens if I am also on the couch, but the kid usually likes her own space otherwise. I tried them in an ex-pen together one night (after Brando had been here about 2 months) to see what would happen having them both in there together. I heard some noise that was really not friendly at all and was escalating and consequently haven't tried that experiment again. That's fine, but it also made me understand why a lot of people said to keep them separated when I'm not around.
I rarely hear any noise from either of them fighting over toys or bully sticks or anything. Which was a surprise because everyone had said it gets pretty noisy with more than one. In fact, there has been absolutely no territory or adjustment issues at all. I have not had to break up any spats on my own, because they are so infrequent. The only time I hear noise is when Ruby is tired and Brando still wants to play and he goes for her neck...then she'll make some noise and he'll stop, but again that is very rare. 99% of the time, when he wants to play, she wants to play and vice versa. And in my situation, that is nearly ALL THE TIME. Let's put it this way, they pant a lot around my house because they run sooo much :D!
Also, in my case, Ruby was somewhat crate phobic. She is sooooo much better with Brando around. No more shaking when it is time to go to her crate...now she willingly runs upstairs and runs right in. I almost cried the first time that happened. She still makes noise on occasion, but in that case, Brando usually starts it because he still cries a little when I leave. However, even that stops by the time I get to the door to leave.
The rest is just money...vet, food, but neither are huge. In fact, my vet cost is about the same as it was with one because I changed vets to one that is further out in the country and has a bunch of basenjis in their practice (in fact they've done surgery on Klassy...and they did Ruby's spay) and the vet cost is lower than the one that I was going to before.
After how it has gone for me, I would always say 2 are easier and better than one.
Oh, and a bonus in my case...Brando fetches...so he is easy to tire out...