HLF

Which reel would be better for a more all rounded setup?
Would 8lbs fireline be advisable for spooling?

I got no experience with these reels but they both looks good from the specs. They use SV spool so both can cast light lures very well. SS SV has more choice of gear ratios and if an all rounder is what you want, then 6.3:1 is what you probably want. It also seems to has higher line capacity too.

I'm not sure what's your concern with fireline, but it should hold just over 100m of 8lbs line.

I tried spooling with my leftover fireline and it was a little stiff and awkward to cast...
Can i spool with some shimano mission complete PE 0.5 12lbs line?

Fireline are naturally stiffer because of the way they're made, I have no experience with Mission Complete but it's pretty interesting to see an 8-strand on low diameter. I'm not sure if it's specifically made for casting but you'll probably like it better than the Fireline. It's not cheap though!