Splash Art Tiers
Below are my thoughts on the different tiers of splash arts Riot has done over the years.
Tier 4(extinct in base splash arts): These splash arts are the very first splash arts. They look very primitive.
An example of this would be Annie's and Soraka's first splash art.
Origin: (2009)
http://imgur.com/pLX9F7l http://imgur.com/6IrzaXs
Tier 3: These splash arts still have an old feel to them, not very clear in their details but look rather good compared to the old splash arts.
Origin: (2011?)
An example of this would be Overworld Malzahar's and Shyvana's splash art.
http://imgur.com/xYT5H4v http://imgur.com/GR3jSKt
Tier 2: These splash arts are in my opinion the best, as they have taken a major step for Tier 3 and look pretty nice. They are very detailed and will most likely not get updated unless another tier of splash art comes up.
Origin: (2012)
An example of this would be Popstar Ahri's and Sona's splash art.
http://imgur.com/OW5vnBv http://imgur.com/BOkdyoN
Tier 1.5: I added this tier in because they are not as detailed as Tier splash arts but look a bit better than Tier 2 splash arts.
Origin: (2013)
An example of this would be Sejuani's splash art
Tier 1(current): These splash arts are being used right now. They are extremely detailed, which sets them apart from Tier 2 splash arts.
Origin: (2014)
An example of this would be Reaper Soraka's and Cassiopeia's splash art.