I've used both and I prefer Regal Select. It is a bit thicker and I think it splatters less.

I just finished painting my finished basement. I used Regal Select for the first time. I used the eggshell finish for the first coat and found it shinier than the Regal. I switched to the flat finish for the second coat. The flat is closer to the Regal eggshell.

The Select is thicker but it doesn't have additional drag. Drying time is a little shorter, and a little less smell. Since it is only $3 more per gallon, I will continue using it.