LoL evolution shards - best levels for each shard?

[ShaneBazTe]

I'm trying to farm the 3* evolution shards in LoL to evolve my 4* characters but seems to really struggle to get any to drop, it's either xp shards or 2*. I'm currently auto-farming LoL Gunner X but I've only had one 3* shards drop all morning. Is there a 'best' level to farm for the evolution shards? I assumed X would be best but can't seem to get any to drop.

[slauki]

level x is always the best for these stuff. you had simply bad luck, they drop just keep playing...