I will do a brief analysis because I don't have the time, but I have a very extensive knowledge on FE.
Ike:
I would say Ike is probably higher than Lucina is (its dumb that there is not specific amounts). Ike being the most popular lord among Western FE fans is not a shock considering he is regarded as being the strongest lord in the entire series, and is the only lord aside from Marth to be a lord in more than one game, and to have both of them released internationally. Ike is also very likable as a character, at least in FE9.
Lucina:
I do believe she is behind Ike in popularity. I think a big reason why she is as high as she is among FE fans is because FE13 is still very fresh in their mind. Most people who played FE13 liked her as a unit and a character better than Chrom. Her strong design similarities to Marth probably help a bit as well. She is very much riding on the accolades for FE13 though, and she is definitely the strongest female lord in the entire series.
Hector:
Definitely the strongest international lord after Ike. FE7 is probably the most popular international FE (though FE13 possibly could have changed that, though we will have to wait until the long-term to see). In most polls I have seen for FE7 and FE series in general, Hector is usually ranked as the most popular of the FE7 lords. He being among the best units in FE7 and having a very brash personality which is popular among Westerners contributes to his popularity.
Lyn:
Lyn is less popular than Hector, though definitely within the Top 5 most popular lords in the West. Like Hector, she rides on the fact that FE7 is the most popular international FE. She is not considered to be as good a unit as Hector, so that is the reason why her popularity is overall less than him.
Chrom:
Chrom being as high as he is probably due the high accolades of FE13 and it overall being very fresh in people's minds. Although Chrom is considered to be a very good unit in FE13, many people who played it complained about him being "bland" or "uninteresting". His popularity will probably fall below that of Ephraim among Western FE fans in the long-run.
Ephraim:
Like Hector and Ike, lots of FE fans love Ephraim for being a great unit. The only problem is that Sacred Stones is regarded as the weakest internationally released FE aside from Shadow Dragon. If FE8 were regarded better by FE fans, he probably would be on par with Hector in terms of popularity.
Marth:
Shadow Dragon was the least liked of the international FE games, so it would follow that he would be the least liked international lord that shares the spotlight by himself. Its too bad FE3 and FE12 were not ever released internationally, else Marth would definitely be much higher than he is. Marth is a good unit in FE11 and did not have to worry about being overshadowed by other lords like Eirika, Eliwood, and Micaiah were in their games.
Roy:
FE6 is probably the most played Japan-only FE game by Western FE fans due to the fact that it is much more accessible than every other Japan-only FE due to its strong similarities to the other two GBA FE games. Roy is the highest Japan-only lord for this reason. I would say less than 10% of Western FE fans have even played a single Japan-only FE game.
Eliwood:
Eliwood is perhaps the most underrated lord in the entire series (or at least among the international ones), both as an unit and a character. He is regarded as being a better unit than Lyn, and on Hector Mode, Eliwood is even debateably better than Hector. Eliwood not standing out as much as Hector and Lyn is probably the primary reason behind him being far behind the other two FE7 lords.
Eirika:
Eirika is a case of a being overshadowed by a much stronger lord within her own game. The fact that FE8 is not as well-received as the rest of the internationally release FE games aside from Shadow Dragon. She is also just not very interesting as a lord to most people, with her being a female version of the typical rapier-using lord arche-type being her most peculiar attribute.
Micaiah:
Micaiah, like Eliwood and Eirika, has the problem of having to share her game with the monster that is Ike. It does not help that she is often regarded as the worst international lord in terms of being a unit, and is often denigrated as being a "mary sue". There is also the problem that FE10 is not as highly regarded as FE7, FE9, and FE13 are among Western FE fans.
Sigurd:
Sigurd being as low as he is is proof that very, very few Western FE fans have even played the Japan-only FE games. Sigurd is often regarded as the strongest lord in the series next to Ike, and he hails from FE4 which is often regarded by the most hardcore of the Western FE fans as the best of the Japan-only FE games. FE4 is probably the most played Japan-only FE game after FE6. Still looking at how low Sigurd is, I would probably now say that 5% or less of Western FE fans have even played the Japan-only FE games.
Leaf:
Leaf is a curious case. He is yet another Japan-only lord, but he also was a unit in more than one title in the series (he is a non-lord in FE4, and a lord in FE5). He is one of the weakest lords in the series (perhaps the single most weakest), so that partially explains why he is lower than Sigurd. However, despite being a weak lord, he is very popular among the few Western FE fans that have played FE5 due to the few having played FE5 end up really liking it (I am an example of this). Due to its intense difficulty, even less people have played FE5 compared to FE4 and FE6.
Celice:
Celice is yet another example of a lord being overshadowed by a much stronger one within his own game. He is probably the most underrated lord in the series next to Eliwood. While he does not start off as good as his father Sigurd, due to his very high growths and receiving the Tyrfing earlier, he ends up becoming a stronger unit than even Sigurd by the end of Generation 2. Celice's very effeminate appearance also probably hurts his popularity, even among the few that have played the Japan-only FE games.
Cellica:
The Famicom FEs are probably the least accessible of the Japan-only FE games due to how dated they are. However like with most FE's with more than one lord, there is one that is clearly more popular than the other. Cellica is more popular than her co-star Alm due to being regarded as a better unit and due to her being more "interesting" since she is a mage, while Alm is just another sword-wielding lord.
Alm:
FE2 is probably the least played Japan-only FE among Western FE fans. He is also overshadowed by Cellica, which explains why he is virtually non-existent to Western FE fans.