Is there fishing line considered a quality line?  Specifically I'm looking at their monofilament.

Also, what is the purpose of their "EZ" series that they have in all the types of line?

 

In my book no, but there's others that like their stuff. 

I like their XXX Mono that comes in a green and black box, but since I found Sunline Super Natural Mono, I haven't gone back to the Spiderwire.

In my experience with it it was not very good. Lots of memory and low breaking strength. 

I have only used their flouro and their braid.  Nothing good to say about the flouro(needed some 6# NOW and that was all the store had), but I like their braid for my spinning reels.  But at, like, $4 a spool you may as well give the mono a try.  I bet if you did a poll around here people would say Big Game mono and you won't be disappointed.  $8 for 900 yards and you won't regret it.

I'd rate Spider wire mono as better than Big Game.  I buy it when it closes out at Walmart.   I only buy 17 and 20 lb and I use it for spinner baits, square bills, lipless cranks, stuff like that.  I abuse it and change it pretty often.

Smalljaw67 (Dan) on here was a tournament fisherman before ill health struck.  He tells me Spiderwire Ultracast Ultimate Mono is the best mono he has ever used.  I've got 12# on two b/c reels that I will be using this year.

Never used their mono but the braid is awesome.

I tried it once for a short period of time. I used the floor, but it was no good for me. 

I have no issues with the braid. I have Ultracast Invisi-Braid on a couple of my reels. I haven't tried mono either.