Dream rifle at 18

A month after I turned 18, I finally decided to pull the trigger and get my dream rifle. Surprisingly, the background check was cleared after one business day. Which optics setup should I get because I want to do a 300 BLK build and an 18-inch SPR build? Also, Is it worth the upgrade to get an SSA-E, or is the Euro Axle good enough? Additionally, before people lose their minds about the Romeo 5, I salvaged it off of my MP 15-22 and haven’t upgraded yet because I am still exploring options. I am excited to finally own a 5.56 rifle and my dream one at that. Lastly, LMT>KAC

A month after I turned 18, I finally decided to pull the trigger and get my dream rifle. Surprisingly, the background check was cleared after one business day. Which optics setup should I get because I want to do a 300 BLK build and an 18-inch SPR build? Also, Is it worth the upgrade to get an SSA-E, or is the Euro Axle good enough? Additionally, before people lose their minds about the Romeo 5, I salvaged it off of my MP 15-22 and haven’t upgraded yet because I am still exploring options. I am excited to finally own a 5.56 rifle and my dream one at that. Lastly, LMT>KAC