Thanks for the answers.

I have only C, D and E. C is system, D and E are for data. From a separate research, I concluded that logical drives don't matter, physical do. So I have only 2 drives to play with.
On the existing server, the log is about 25 GB and the tempdb may grow to 40+ GB, still far from the 2 TB capacity of D: If I don't place tempdb next to the transaction log, I put it on the slower drive with data. Is it really a better option? Unlikely.

Splitting data and indexes apart is one of the old performing-tuning advices. Since it is disputed if it is still a valid advice or not, I am fine with dropping this idea for something reliably better.

So, the question is what is the best use of about 1.8 TB of SSD RAID1  and 12 TB SATA RAID10 with 0.2 TB of SSD reserved for the transaction log and tempdb?

The database is for both reading and writing intensive..