So you want a Liberian President for a list or story.
You've found the list of Presidents of course and then the list of Vice Presidents. You then scrolled through the list of defeated presidential candidates from the african elections database, so the likes of Samuel Benedict, Edward Blyden, Anthony Williams, Thomas Faulkner and other such radicals who ran against the one party rule of the Republican/True Whigs. And later the likes of Tipoteh, Cheapo, Matthews during the civil war and then Brumskine during the last decade
But all that is a bit too obvious for you, you want to know about the people who never got remotely close to power in otl but could have done.
Well my friend, you've come to the right place.
First of all from 1848 to 1869, you saw uncontested rule by a light skinned merchant elite. This could be challenged, John Day I think is a natural choice for an outsider bid at the presidency, but within those years changing the exact example of the elite to hold the Presidency doesn't matter much. A Republican rule forever is nepotism central, so lots of Roberts, lots of Johnsons, lots of Tollivers etc.
What's more interesting is when the opposition, the party of the farmers and the dark skinned new arrivals, began to come together in the 1860s. They first won the Presidency under Edward Roye, but he was overthrown in a coup for being too radical and it's Hilary Johnson in the 1880s who really ends the light skinned and dark skinned feud and cements the Monrovian settlers as one people represented by one party.
There's a bunch of other possible candidates for Roye and Johnson figures which immediately tells you where this Liberia is. On the one end of radicalness you have Edward Blyden, who wanted to extend the franchise to all the interior liberians and legalise polygamy etc. Also on that Blyden wing of the political spectrum you also have John Payne Jackson, who is best known for running an anti imperialist newspaper in lagos and was one of the founders of Nigerian nationalism, but was born and bought up in Liberia and would be an obvious choice for a 'continuity blydenite'.
On the other wing, you had 'the Christianise and conquer the interior' wing. That would be represented by people like Alexander Crummel (a minister) and Benjamin Anderson (an armed explorer). A good continuity Crummellite is Selim Aga, a freed Sudanese slave raised in Scotland who worked with British explorers like Richard Burton and William Baikie, he lectured on Africa in the UK and USA and campaigned for increasing investment in the continent. He died fighting the Grebo having moved to Liberia to pursue a political career.
In between those extremes, William Spencer Anderson who was assassinated while on trial for corruption would be an obvious successor to Roye if you want to avoid his otl vice president, James Smith.
There's also the Marylander faction from the failed independent state of Maryland. William Prout, Boston Drayton and Joseph Gibson. If any of those come into power, it would indicate a shift of power away from Monrovia.
Talking of which, we also have the native Liberians themselves. In the 19th century you had resistance from the likes of Doblee Zeppey and Fahn Kambo while in the early 1900s you had Suah Koko and Gueh-Gueh. But these are much more likely to burn Monrovia to the ground then run for the President. An extended franchise probably still means a settler dominated state in the same way few of the enfranchised blacks actually voted in the Cape Colony.
You're looking at the early 20th century before you start seeing western educated natives capable of climbing the ladder. In the 1920s you had Momulu Massaquoi, the Val Liberian diplomat to Germany and Henry Two Wesley, the Grebo Lawyer both of whom were model minority members of the establishment. Massaquoi was African Nobility who converted to Christianity while Wesley was much more of a self made man, but both are interesting choices for the first native Liberian President. In the 1930s, you have Plenyone Gbe Wolo, a Kru Headman, who graduated from Harvard in 1917 and attempted to set up a western style school in the interior before it was shut down. You also have Juah Nimley who fought the Sasstown War against the governments attempts to sell the Sasston Kru as slaves to Spanish colonies. Good friends with both of them and one of the most impressive characters of 1930-40s Liberia, you have Didwho Welleh Twe. Twe was educated in America, having left Liberia at 21 and helped Mark Twain write his anti colonial works. He was the voice of indigenous resistance to the True Whig Party and if the revolution had come three decades earlier, he'd have taken the presidency. He's a genuinely fascinating figure.
In the 60s and 70s, you had Matthews, Cheapo and Tipoteh running the opposition parties but you also had Alfred Porte, the Barbadian journalist, ripping the government to shreds in the Crozerville Observer. He's a good choice for a figurehead in a limited revolution and an attempt to open up slightly.
In the post Civil war era, I think probably the most interesting choices are the anti-logging environmentalists, who have a decent status and would probably have broken through more if Liberia had less more obvious problems. So that's Silas Siakor, Alfred Brownell and Alexander Peal.
And you can also look at the diaspora to see people who might have stayed in Liberia without the civil wars, so Jehmu Greene (the token black democrat on fox news shows) as an alternate Ellen Sirleaf Johnson and in terms of alternate George Weahs, there's always Richelieu Dennis, who ran a fashion company in America before being sacked for running a toxic work atmosphere. Both choices tell you something straight away.