I've got 4 different strains in a single reservoir, top feed DWC tent, and 2 in another similar tent, all in multiple plant reservoirs.
I never grow 2 plants of the same strain during the same grow.
As long as the plants have similar expected heights, there isn't a problem.
I grow 2 taller plants in one tent, and 4 shorter ones in the other.
They can all thrive on the same food and same light distance.
My advice is to grow several different stains.
They're all good, and the quicker you try a lot of them, the sooner you'll find the ones you like best.
I prefer indicas, so 24Carat, Skywalker, and StrawberryNuggets are among my favorites.
The only mephisto sativa I've tried is FantasmoExpress, and it was excellent.