Diamond contests always leave me underwhelmed. And i think it is the same for most.
Tiers - ok. Just not bothered with this contest type so will be in save mode. Could max out, but probably wont as will spend no diamonds.
Ranks - Not that exciting. It does not help that new toon is not great imao, as much use as a three headed snap dragon.
The good - link to forums worked and info accurate.
Contests types to consider to replace the diamond style. Variation would be nice.
Quest style contests
Earn gold/tokens contests
Spend gold/tokens contestd
Guild wide contests
Add guild elements to existing contest types eg prizes for tiers and ranks according to guild totals (in addition to individual totals). Award these on points contributed so those that put in most get most.