Louis de Bourbon son of Henri Jules de Bourbon, Duke of Enghien, and Anne Henriette of Bavaria (granddaughter of Elizabeth Stuart) b1668 - not a perhaps attractive choice given his looks and health but his English great grandmother might make up a little for his Catholicism to the English. In OTL he married in 1685 the daughter of Louis XIV and Madame de Montespan. He is probably the only really strong French candidate.
I think Charles would try to push the Bourbon match, being as you mentioned strongly aligned with France politically and by marriage, but would ultimately realize Parliament wouldn't go for it.
A Hapsburg or Spanish match are going to elicit memories of Bloody Mary to the English I suspect which won't go down well.
Absolutely agree.
Politically Charles veered towards France throughout his reign - it was this in part that poisoned his relationship with the Dutch - the 1677 marriage of Mary and William was part of a settlement of the earlier Dutch war and an attempt by Charles to broker peace between William of Orange and Louis XIV.
Anne's marriage to George of Denmark was encouraged by the French because Louis believed the English and Danish navy's would be a bulwark against the Dutch - it might be that instead of Anne the Danish push for Elizabeth and perhaps he gets Anne as the King is reluctant to tie his daughter at just 14.
This sounds plausible. Okay, so Mary and Anne would likely keep their OTL matches. Definitely Mary if not Anne.
Don't forget that in 1685 Louis XIV is pushing for his sister in law's claim to the Palatine to be recognised so he might himself favour a pro-german alliance for the young English Queen as part of his hope that Elizabeth Charlotte's claims to her brother's holdings should prevail over the distant male heirs of the Palatine. This will have a major impact on the nine year war and will perhaps see switching alliances.
So, maybe if Louis helped push the Danish match, he might encourage Charles to marry one of OTL George I's younger brothers or another German younger son especially if he accepted the Bourbon match wouldn't go through or would rather Louis de Bourbon marry his own daughter.
So Elizabeth's choices are the five younger sons of Ernest Augustus, Elector of Brunswick-Lünesburg,
1. Friedrich Augustus of Brunswick-Lüneburg (1661 – 1690)
2. Maximilian Wilhelm of Brunswick-Lüneburg (1666 – 1726)
3. Charles Philip of Brunswick-Lüneburg (1669 – 1690)
4. Christian Heinrich of Brunswick-Lüneburg (1671 – 1703)
5. Ernest Augustus of Brunswick-Lüneburg (1674 – 1728).
6. Louis de Bourbon son of Henri Jules de Bourbon, Duke of Enghien, and Anne Henriette of Bavaria (granddaughter of Elizabeth Stuart) (1668 – 1710)
7. Augustus, younger son of the Elector Johann Georg III and Anne Sophie of Denmark (1670 – 1733)
8. Charles, Duke of Mecklenburg-Güstrow (1664 – 1688)
9. Philip William, Prince in Prussia/Margrave of Brandenburg-Schwedt (I think this is who was mentioned earlier?; 1669 – 1711)
I would imagine that if Charles comes around to a German match and has Elizabeth betrothed before he dies, we would likely see Elizabeth married to one of the three brothers in the middle - Friedrich being eight years older than Elizabeth and Ernest being seven years younger. Charles might let Elizabeth choose a brother (also side note: Max and Ernest are the only two who have wikipedia pages? It is difficult to find more info than name and birth/death dates on the other four). I see her going for Max if only because he and Ernest are the only two with portraits.
Max as consort is interesting. OTL he and his brother Christian Heinrich were involved in a plot in 1690 after their older brother Friedrich died to gain back what they saw as their rightful inheritance, having agreed in 1864 to allow the family to begin primogeniture and thus not gain anything when their father died. Max was imprisoned for a year and then exiled from the Duchy of Brunswick-Lünesburg. Probably not an issue if he's married/betrothed to the Queen of England but he's certainly going to be a character, and I could definitely see him stirring up trouble in England (also King/Prince Max sounds quite jolly).
If a match is not finalized before Charles' death, I think James will try to push a Catholic match, though not necessarily the Bourbon one still. Catherine would probably also want her daughter to marry a Catholic, even hoping for a match back into the Portuguese royals, but might be pragmatic enough to come around to the necessity of a Protestant match. I think Elizabeth and Monmouth would be gunning for a Protestant match, and Elizabeth might have more freedom to pick a German Protestant prince of her choice if she promises the immensely relieved Parliament to marry Protestant. In which case, I think she might eschew her Stuart cousins and pick Augustus.
Augustus is also quite a character. One would hope he would know better than to cheat (openly) on his wife the sovereign Queen but that could also become messy (and interesting!). And if Augustus' older brother still dies as in OTL, we'll see the merging of Saxony and Britain, which also very interesting.
Coming back to titles, Philip was given the title 'King' while married to Mary I but given how unpopular he/they were, might the title 'Prince Consort' emerge long before OTL Victoria and Albert for *Elizabeth's husband?