I want to build several decks for casual playing. My plan is to choose a set, buy 6-7 of each common, 3 of each uncommon, maybe some cheap rares, a stack of basic lands plus whatever tokens I need and use this to build a deck for each single colour and for each pair of colours. As I have never played Magic a lot, I don't know the sets so choosing the set to build this from is hard for me.
I am looking for the following:
coherent theme (I was thinking about Modern Horizons but cards from all over the place drove me off it)
good availability (easy to buy, not very expensive, a lot of bulk rares)
possibility to build 15 decks (mono and two colours) of similar power and playing differently, with all major Magic deck archetypes represented
Which set would you recommend for this?