What RNA-Seq expression value would be closest to Microarray equivalent? I know this question may seem strange.

I'm using Spearman correlation between gene expression profiles for various reasons (I won't go into details here). As a result, I often compare RNA-Seq and Microarray samples.
For preliminary analysis, I usually grab what version of the data is easily accessible (RPKM, FPKM,...), but I'd like to dig a bit more.

Intuitively, I'd think a value similar to RPKM or such would make more sense than raw counts, which is why I usually convert raw counts to RPKM (I know they're considered obsolete for statistical analysis of the data, what I'm doing relies on the correlation)

So I ask what RNA-Seq gene expression value would be closest to a microarray equivalent ?

i.e. What would (theoretically) maximize correlation between gene expression of the  same sample profiled with RNA-seq and microarray. RPKM ? FPKM ? TPM ? etc.
I think it is very hard to say which are the closest because they are not really comparable. But since you are using Spearman correlation, I guess RPKM, FPKM, and TPM do not change the order of gene expression levels. You might also want to normalize RNA-seq and microarray data so that they are more comparable.