Upgrade tonearm


Looking to upgrade my tonearm on my Sota Cosmos IV. I am currently using an SME 309 with Ortofon Kontrapunkt B cartridge. I also have a Lyra Delos and others. I do like the SME, but am considering an upgrade to get into supertable status. Considerations so far are Helius Omega, Basis Vector IV, Triplanar and Graham Phantom 2. Anything else I should consider that would work especially well on a Cosmos?
I will probably upgrade my cartridge later, so dont feel restricted to my current cartridges.

Of course, I have no opportunity to audition, so making a multi thousand dollar purchase by asking others is a little daunting, but, it is what it is.
manitunc
A number of years ago, I had a Helius Orion tonearm. It was the most problematic component I ever had. It went back to England a number of times, and in the end still had binding bearings. Maybe they figured it out, but for ME, I wouldn't get near a Helius arm again.
I have picked up a SME IV and Helius Omega. I have an Cosmos armboard for the SME, but need to send the Omega mount to SOTA to make up a Cosmos mount for it. I dont want to drill into one of my others, as they are to pretty. I have made up an oak armboard for the Omega. It sounds very nice with a Delos so I expect it will be even better with a proper Cosmos mount.
Sota often uses and recommends SME. There are no dealers around me. I was hoping to get input from actual Cosmos owners who have had good experiences with something other than an SME.
Give the designer a call or email and ask him for suggestions. Talk to the dealer if you feel they are competent. The dealer should be able to make credible suggestions.