They’re both the same thing, only difference is the new graphics, soundtrack and steam workshop, so It’s going to depend mainly on whether you want to play with ASCII or not. Keep in mind that v50 (current version) is lacking some community made utilities and no custom tilesets were ported over as of yet, so if you want to use them you’d have to play v47 (pre-steam version) but you’d be missing out on the new UI and controls which are both a massive improvement. Honestly, the paid version would be easier to learn just because you wouldn’t need to decipher the ASCII, but if that’s not a problem go with the free version first.