CSGO and Siege both require you to analyze the situation and use your knowledge of the map to defeat the enemies. Althought CSGO has many perks like community servers making the game different and Siege has some funny moments.
I like Siege as its more challenging than CSGO to me.
CSGO, I couldn't seem to get into R6. The game seems much more complicated, more long paced and everything.
I got around 1 hour playtime on there and got bored. Maybe you just need to play more of it to enjoy it.
I've had years of experience with CSGO, thousands of hours of playtime
And most of all Counter Strike games we're basically my childhood along with GTA, Age of Empires & more.