Between Kound? and Koulibaly, I think we would be hard done to not pick both up considering we have news of this supposed 150-200 million euro warchest. Not saying it would be responsible to spend this entire amount. But with Lenglet, Umtiti, and Pique being put out to pasture or not trusted to be a starter this coming season, we are left with Eric Garcia, who despite what everybody thinks, has not shown much to trust him, especially giving away a few penalties and getting mugged off by every player. Araujo who is a physical specimen, but his injury list, while not being lengthy, is getting worrisome. Christensen I have no issues with. I wouldn't consider him a starter, so hopefully he was not brought in with that intention. Araujo should be undisputed starter with either Kounde or Koulibaly partnering him as a LCB. That begs the question of dropping one of them Kounde or Koulibaly if we do decide to get both. Unless Xavi plans on going 3-4-3. Which I could see as both Araujo and Kounde can play the RCB/RB role effectively
Getting both is absolute overkill and not necessary at all. Even if we had Van Dijk and Dias at CB, it won't mean a thing for our defense if we'll have Roberto and Alba/Alonso as our full backs. Getting a second CB in besides Christensen is necessary (to force out Pique), but we can't put all our eggs in one basket, we have to improve our full back and defensive midfield area too, and come to think of it, goalkeeper too, to really become defensively solid. There's SO much more work to be done on the rebuild, we basically have to get 5/6 new starters just in the defensive area in the next 1-2 years. Not to mention actually needing a new striker/right winger this summer already, ideally both.
Things could change of course, if Xavi is planning to go 3 at the back full time, which is entirely possible, especially considering the kind of players we already got and are still targeting (basically all of them do better in a 3-4-3 than in a 4-3-3) and in that case it would be very beneficial to go for both of them, but I still can't see us going there. In that case I see Azpi (who I think will come) fighting with Garcia for that 4th spot, and Pique also staying as the emergency 6th. To be fair, Araujo-Kounde-Koulibaly back line would be pretty sick.
But in normal circumstances, Garcia, although not impressive, is more than good enough for that 4th CB spot (cause he ain't leaving anywhere), with Christensen coming in to be the 3rd choice, also being a very solid option for that role. And one of Koulibaly or Kounde to partner up with Araujo. My personal preference of the two is actually Koulibaly, not only because he'd be as half as cheap, but I also like his profile more, a big, strong and tough leader type. And he's used to playing LCB, while Kounde and Araujo both play RCB, and have been for years, so one of them would have get used to the whole other side, which can become very tricky. But if it does end up being Kounde, I'll trust Xavi's judgement, especially since he seems to be absolutely determined on getting Kounde over everyone else and partnering him with Araujo. I have no problem with the club going for the manager's choice.
Of course because of the age Kounde is obviously the more long term solution, at least hopefully. I just hope he doesn't turn into Lenglet 2.0, I've had just about enough of French CBs and players in general in recent times, especially when we haven't even gotten rid of the original bums (will probably be rid of all three left this summer, thankfully). I know that's unfair to Kounde to label him like that, just because he's of the same nationality and will follow the same career trajectory as Lenglet, but it's not just about that, his play style also doesn't fill me with confidence, he can be quite irresponsible and prone to mistakes.
In any case, after getting Kounde/Koulibaly we have to focus on full backs, how great it would be to go for someone like
Gaya for just 15-20M (he still hasn't signed a contract extension, so I'm assuming he is open to leaving for a top club, it is his last chance basically, and Valencia also really need the money, so maybe his loyalty can be tested after all) and
Pedro Porro for like 30M, as he just got bought by Sporting a few months ago, so he's no longer unavailable/tied to Man City in any way.