I agree that there is no perfect match for Elizabeth (as much as I've argued Charles II is), and that IOTL she made the best decision. But staying single, at least from my vantage point here just isn't viable. She needs to secure succession, if not for herself than for her people (and I'm sure Parliament would make it abundantly clear in their view). Their pressure might piss her off, but I think she'd ultimately come to agree with them. Succession ITTL isn't nice and clean to the Stuarts because of their personal union with France, so I think Elizabeth would find it better to suck it up, sire an heir (even if she only has one daughter), and prevent a massive succession war, which could devastate her country.