I think it's Montreal, but it should be Ottawa. Stone/Karlsson + 4OA (or a top 3 pick next year if they give up the pick this year) is a better and younger core than what Montreal has, but the franchise is such a gong show and it's doubtful they can keep that core together (or find a supporting cast if they extend them). Problem is the money, it's quite possible Karlsson is gone even if they can afford to offer 12X8 and if they extend Stone and Duchene they're running out of money without much left to elevate that core which just finished in the basement. At the very least we know the Habs can spend to the cap and back up the money truck if necessary, while the Senators are doing things like getting Bodker and Gaborik to save a few million in real dollars and reach the cap floor.
People overreact to Weber's contract too, practically speaking the remainder of the contract is 7.8X5 for his 33-37 seasons. Going into the upcoming season he has 4 years paid 6M, 1 year paid 3M, and then 3 years of 1M. If you think Weber is playing out those final 3 years for 1M each after making 107M the prior 11 years I have a bridge to sell you. 7.8MX5 under an 80M and rising cap isn't really some franchise damning albatross. It also doesn't make any sense as a dealbreaker in this comparison, if Weber is supposedly going to kill the Habs then how do you pick the Senators with the Ryan contract? Weber is still a useful top pair defender, and Ryan costs nearly as much and only 1 year less to be a 3rd line winger. I just have a hard time imagining Ottawa being able to build something without a new owner, and I think the Habs can fixing the "hockey" side of things is much more likely than the Senators either fixing the business side or finding a new owner. If they extend Stone/Karlsson/Duchene as their core at say, 8M/12M/7.5M, those three contracts plus Ryan are going to cost 35M in actual dollars and at that point you're left with maybe 25-35M to fill out the remaining 19 spots on the roster.
If the Senators could spend to the cap it wouldn't be an issue and I'd much rather take over a core of Stone/Karlsson/Duchene as a new GM, you could just hang on to Ryan and still be more or less fine under an 80M+ cap with that core. But it seems like the Sens internal budget is something like 60M right now and that's tough, especially because the knock-on effects are things like losing out on Ceci for Hall because you need financial approval, greatly reducing the return for Karlsson by including the Bobby Ryan contract, downgrading from Phaneuf to Gaborik to save cash, trading Zibanejad for Brassard to save cash, ditching Turris to save cash instead of having both Duchene and Turris, or trading Hoffman for Boedker to save 1M and reach the cap floor (his cap hit is 4M and salary 3M) instead of getting half decent picks from Florida. That's a long line of bad moves that mostly happened due to financial constraints, and a GM in Montreal wouldn't have to deliberately lose trades just for financial reasons.