We've run leafs forever and had Afcos, Landrums, Black  Magic, Speedway Motors and many we've built from junkyard stuff to suit our needs and, frankly, couldn't tell much difference in performance or longevity.
   Just get the rate you want and keep them maintained and replace them when they get bent laterally or the arch starts to go.  Higher priced ones never seemed any better than the cheaper ones.  My opinion from a lot of experience with them. Good luck.

I don't know that it matters what kind you buy, but if you're not having David Hays at A-1 Spring re-arch the RR every 3 or 4 races, your car is probably not at it's full potential. That's one thing I learned driving over there. I'd never re-arched them that often, but you can feel an increase in side bite after he does. RR about every 3 or 4 races and LR every other time you take the RR in.

throw m in the trash and mount a coil ! JK guys . my limited experiance says landrums ................ ! never tryed rearching them , pulled em out at the end of the season and chkd arch , within a 1/4 in

   I  agree with jimss21x about keeping them lubed up and especially with AJ55 about how important mounting is.  Splay on each side, front to rear mounting heights are both extremely important.  You can make a car tight, loose or all kinds of funny if you don't do it right. Sure have seen a lot of really bad mounting. There's a lot more to running leafs than just the rate.
  Can't run monos in our class anymore nor the composites  in CA.  Nevada tracks are mostly legal on composites and guys I know that run them love them.  Of course they're about $300 a pop.
  As for rearching I haven't done it for years.  Shops up here charge about $80-100 each.  When a new stacked leaf from Landrum is about $100 it's not worth it to me.  Did my own when I was young & broke with an anvil and a 8 lb. hammer.  Arms looked like Popeye but felt like Olive Oyl's when I was done.  If I had A1 Springs for a sponsor I'd feel different.