Hey Pazuzu, good to see you again.
I play the Steam version these days since I couldn't get TQ/IT to run on my machine with AE also installed. I enjoy all the expansions, though the Eternal Embers one is a bit empty of foes in places.
As for what machine to get I'd say a PC over a laptop simply because not only will you be able to run TQ1, but also should be able to run the upcoming TQ2. Yes,we're getting Titan Quest 2 at last! Not sure exactly when it's going to be released yet, but the dev team are doing monthly (more or less
) updates on things to do with the game. We had a blog on the music for the game in December and in the last few days another blog about world design. We don't yet have the actual minimum/recommended specs for the game so take the 16/32 gb ram with a pinch of salt.
https://store.steampowered.com/app/1154030/Titan_Quest_II/