Best Tonearm Upgrades for Linn LP12

I've just purchased a used Linn Sondek LP12, which I selected because of the high starting quality for the table and all the upgrade possibilities. I have the Valhalla Power Supply and a Basik Plus tonearm. Currently, I'm using an old Grado G-1+ cartridge and I will upgrade to a Dynavector 10x4 or 20X-H soon.

My questions are: Which tonearms will make the greatest improvement for the least money? And which tonearms are great matches with the turntable?