I agree on Jeff Parker. It’s a shame he hasn’t had the really big break out hit he deserves. I thought Aquaman might be it, but it seemed to sink in the New 52 DC muddle.
I would suggest Fred Van Lente, who is a consistently witty and interesting writer that seems quite happy to work on more niche titles, mainly at Valiant these days, but used to do B/C-list titles for Marvel that were always vastly under-appreciated. Marvel were a fool to let him drift away elsewhere instead of getting him on a core title.
And the other one is, of course, James Roberts, whose work on More Than Meets The Eye would be winning all sorts of awards if it wasn’t a Transformers book and thus written off most of the time. I think it did actually win a Comics Alliance award at the end of last year, which is nice. Roberts mixes well-read political allegory, human drama, excellent long term plotting and genuinely laugh out loud humour to make one of, if not the best comics available today.