Strong, smart, intuitive, and very good with a gun. Wash is, of course, head over heels for her, and the feeling is mutual. Best girlfriend ever. Of all time. This does, however, come with a bit of a catch - given Wash's mental state, codependency and especially romantic relationships are very solid and very important, and losing people tends to trigger Epsilon's memories in him - which is to say, when Ziva woke up and disappeared for a few days, he handled it extremely poorly. A romantic relationship is very much a double-edged sword for him, but it's a temptation he's not strong enough to resist.
My Little Pony: Friendship is Magic
As far as Wash is concerned, Luna is a good friend and a solid ally. They started working together not long after they both arrived in the realm of dreams (Wash picked her for his partner because she looked like a kid who was afraid she'd be picked last for dodgeball), and Wash was completely blown away by her magical prowess, namely because he was still getting used to the idea of magic at the time. He was even more blown away by the fact that she could walk into his nightmares and soothe them. They wound up trading backstories, making Luna the only person in the city who knows exactly what happened to Wash. She can be haughty and illogical at times, but as far as Wash is concerned, her good qualities far outweigh the bad.
North and Wash have been friends since Freelancer. As far as Wash is concerned, North is a steady friend and he knows he can go to North with just about any problem. Recently, their relationship has hit a rocky patch, as North's point on the timeline is much further back than Wash's, and Wash was reluctant to tell him anything about his future. North got tired of Wash's lying and evasions, and they had a rough time communicating for a while. Even after Wash apologized and promised not to lie to North anymore (a promise that may or may not be kept), they still have a rough time talking as easily as they used to. (North still doesn't know what happened to South, and that's still a stumbling block for Wash.)
Carolina is Wash's former CO from Project Freelancer, a rank that would have earned her a lot more of his respect were it not for present circumstances. She's from a further point in the timeline than he is, and arrived in the realm of dreams angry with him for something he hadn't even done yet. His already sour relationship with Epsilon didn't help when she took the AI's side over his. It's been an uphill battle since then, especially with Wash's current lack of respect for the Project - and, at the moment, his irritation with Carolina for failing to see that her cat was throwing a tantrum and that he hadn't hurt her, goddammit, quit blaming him for her cat's bad behavior. York's disappearance may have mended a bit of that with shared grief, but it's still very much a rocky relationship.
Epsilon is the AI assigned to Wash during Project Freelancer. Because Epsilon was markedly unstable, his insertion literally drove Wash insane. Not a great basis for a relationship. For years afterwards, Wash just saw Epsilon as a piece of computer equipment and later evidence, never as a person. To an extent, he still does - it's hard to humanize the thing that fucked you up badly enough to put you in a straitjacket, even if it wasn't Epsilon's fault. It doesn't help that Epsilon has an abrasive personality and Wash has no patience for him, or that Epsilon can spill information that Wash very much wants to keep hidden (South's untimely demise, anyone?). They've clashed before, and it hasn't gone well. However, to some extent, Wash does feel some responsibility for Epsilon - he is Wash's AI, after all, and Wash has pulled him out of more than one scrape, even for nothing more than a sense of duty.
Wash has essentially adopted Namine. It's a thing. The first time he met her, he flipped a table over to provide her some protection from Nightmares and proceeded to take them all out. He's gone by the tea shop where she lives and works just about every day since, partially to get coffee and partially to check in on her. He's extremely overprotective of her, and he cares whether she's happy or not. (The prose refers to them as not!Dad and not!Kid.)
Wash has a healthy amount of respect for Eraqus. He seems to have a good head on his shoulders, and Wash has seen exactly what he's capable of in battle. (It's definitely a better idea to have Eraqus as an ally than an enemy.) He can't say he always agrees with what Eraqus says or does, and they've definitely had their arguments, but Wash would still rather have Eraqus at his back than a good number of other people in town.
Aqua is smart, capable, and familiar with some of the worlds that have shown up in the realm of dreams, which has earned her a few points in Wash's book. She's also said some incredibly stupid shit, which has put her right back in the negative, as Wash isn't the sort to forgive that kind of thing. All told, he has a rather neutral opinion of her.
Even may have the occasional good point sometimes, but he presents it in such a way that Wash can't help but see him as a complete snooty jackass. Plus, he's a lot of fun to troll, provided you have the patience for it. A++, will bait again, if only because getting a rise out of him is so goddamn amusing.