I was thinking of brewing a deck along those lines too, but just haven't gotten around to it yet.
I'll post my list and my thoughts when I do. But congrats for beating me to it kryder.
A card that could be good in a deck with so much lifelink is Famished Paladin, which can be a pseudo vigilant creature that can block well against 2/2s and 2/3s.

I need to autocard here to see why you made that swap. Warleaders are great cards in a lifegaining deck so let's see here.....
Conclave Tribunal.
.... I don't know. I'm a little on the fence here. I see you want a little removal but at the expense of what should be a key card in the deck?
Don't know about that. What you first built is where I was leaning for a grinder also. I've had great success with the white precon Tactical Advantage and playing it has reminded me how muck I like playing white decks some times. I haven't built a pure white since I started playing Arena.

Well, it's official, mono-white is the new mono-red. Just went 7-0 in a constructed event and man does this deck kick-ass. Pulled off some wins I shouldn't have won, with double pride of conquerors and also managed to make some incredible comebacks (especially the last game where I was stuck at 2 land forever).

So this is my list:

Lands (22)
22 x Plains

CMC 1 (16)
4 x Healer's Hawk
4 x Legion's Landing
4 x Leonin Vanguard
2 x Haazda Marshal
2 x Skymarcher Aspirant

CMC 2 (10)
4 x Pride of Conquerors
4 x Ajani's Pridemate
2 x Famished Paladin

CMC 3 (8)
4 x Benalish Marshal
4 x History of Benalia

CMC 4 (4)
1 x Ajani, Adversary of Tyrants
1 x Leonin Warleader
2 x Conclave Tribunal


Not far from kryder's list., Although his latest list has gone more flying based than mine.
I also felt the need for a couple of removal spells and conclave tribunal is huge! I can definitely get behind adding another.
Famished paladins have been consistent and are knights which came in useful with the histories.
Pride of conquerors is such a blowout card... It just does 20+ damage or clears opponent's board all too often.

I think this is T1 material. Could use some tweaks, but I think it's just more consistent than boros and lots of fun.

Enjoy!

I actually got my fifth history of benalia in the GW starter deck and opened a sixth in a pack... Damn RNG!

I really like these White decks, I think that will be the next deck I try when I have some of the rares.

Quick question though, why Conclave over Binding? I am guessing it is a mana issue at 22 land? What permanents are most problem some for your deck? Guessing big creatures mainly?

Yeah, casting it for 0 is the upside because it's easy to flood the board.
And it hits everything, nasty blockers, PWs, etc even when your mana screwed.

So, I have been trying this deck, and it really is that good so far, and that is with me missing some rares.

Sweepers really hurt though. Pride helps, and thankfully I have only been hit with Fiery Cannonade and not Deafening Clarion twice. Racing to the Cities Blessing vs Izzet is pretty key (assuming you have Pride in hand).

I thought about Boros just for Taijic for some sweeper protection, but that just pulls too much consistency out of the deck.