So much information on the internet says basenjis are not smart. That is simply not true. I like to believe that basenjis CHOOSE to show you when they are smart. But if you are consistent with training, you will find that you can have a wonderful smart dog that will listen to you for most of the time Basenjis are not the kind of dog (are any?) that you can use forceful training methods on. They like reward based training - getting small treats of food (1 kibble or tiny treat) when they do something you have asked them to do. And you also must praise them a lot when they do something well. They work best with positive reinforcement training.
Basenjis do socialize well with other dogs, but of course that depends on how the breeder raises them and how you continue to train/raise them. I believe puppy socialization and puppy obedience classes are a must. They will like most dogs, size is not important, providing you have done the work to make sure they are well socialized.
One other thing that is critical to tell you is that basenjis should NEVER be loose (without a leash) unless they are in a fully fenced area. This is not the kind of dog that you can walk with without a leash on. They have a very high drive for hunting, and if they see a leaf blowing across a street, a squirrel, rabbit or other small animal, they will run to get it, not even thinking about cars or other moving objects that could hit and injure/kill them. For this reason, if you have a back yard, the yard must be fully and SECURELY fenced with not even a little area a basenji could get through. Otherwise if they see an opportunity, they will dig under the fence and get loose. You must also really control them when you or others go out of/into the house. They can tend to want to bolt outside. Sadly, there are some members on this forum who lost, or worse had their basenjis killed by a vehicle, when it darted out the door.
I'm not telling you all of this to scare you off of the breed. You just have to do all of your homework BEFORE you get a basenji.