Hmm, I think you should expand your guide more, I know you just started it, but I'm just saying. Talk more about the masteries and runes and show other options. For example, you can take Greater Seal of Health and Greater Quintessence of Armor so Leona will be more tanky.

For the items, as the person above said, I also believe that Frozen Heart is a better choice for Iceborn Gauntlet and I understand Sunfire Aegis as I like to use it specially when my team/ADC is not that great. So maybe you could explain better the circumstances, it can avoid misunderstandings or people talking about it over and over again.

I will hold up my vote for now as I know it takes time to improve a guide.

I can't agree with the Sunfire Aegis either. It should never be a choice over Randuin's Omen. It's never really a tank-support's job to bring more damage, more so Leona who doesn't have any damage the later the game goes on. Sunfire Aegis should only ever really be bought early, since its damage is so small that it gets weaker as the game goes on past early-mid game in the same way.

In short, Sunfire Aegis is for those champions who can farm well enough to get it early, i.e. Not supports.

Randuin's Omen is reliable no matter when you get it. Iceborn Gauntlet is a pretty awkward buy as well, especially when you can turn Glacial Shroud into Frozen Heart.

MS Quints are a bit weird for me, but doable, I guess. A better setup would be Health Seals and Armor Quints.

I've played Leona from Bronze to Platinum, so I have experience.

Thanks for the feedback!
I didn't really consider hurting the adc's farm with your Sunfire Aegis, but since you'll most likely get a Relic Shield it doesn't matter all tóó much. I still switched them up in the core items as I think you're right.
All of my guides are permanent under construction as I keep remembering and updating things. It'll expand with time. (Did you make sure to read my general support guide? as there is the most information to find)

Not sure I agree with that, this guide does have "low elo" in the title. In low elo the more damage a support does the better. However, if you get it too early, it really hurts your ADC's ability to farm, so I am in between. Therefore I can't really vote one way or the other.

EDIT: Upon reading the guide you did indeed list that you can either get Sunfire OR Randuins. Therefore I am not sure why you were downvoted for not recommending Randuins. I would recommend you switch Sunfire with Randuins in your core items, as I think he downvoted the second he saw Sunfire without reading the guide, which, in his defense, you kind of set yourself up for. However, in the meantime enjoy my upvote to balance it out, assuming you will fix your core items to better represent a higher elo Leona build. (AKA switch Sunfire for Randuins in core and expand your guide a bit.)

sunfire cape support is a free -1. Randuin's is better in EVERY aspect for a support.