I'm using Tiko's Bone Collector for Arena Grinding, and Chapuz's Limitless Speed (Slim version as base but some stuff switched around for more Hourglass Speed, with everything but 4 Shields and a Quantum Pillar upgraded) for FG. I would love to run a Hourglass-Druid Deck but I don't have anywhere near enough money (and frankly anything 3 HP or below basically insta-dies now the way I see it).
As for my Electrum, I'm poor (obviously that's why I'm grinding!).
Besides the above all I got are some Rares; off the top of my head:
2 Shards of Serendipity
3 Shards of Gratitude
1 Shard of Sacrifice (only 5 more for DialSoSac....)
2 Shard of Void
1 Shard of Readiness
1 Pulverizer
2 Fahrenheit
3 Owl's Eye
2 Eternity
1 Arsenic
At the very least where the shards are concerned, as far as I can notice, the majority (by number) that I possess are not particularly popular for the current meta decks.