I am going to get a Maya wrap or a Maya pouch.
I prefer my pouch just because I find it a little easier to get on and off.
I have both and really prefer the pouch for everyday use. Its super easy to pop my ds in and out of at a moments notice. I just find the ring sling too much work most of the time. Also its 100 degrees out here- the less fabric the better!
I have a Maya Wrap ring sling and a Mama Kangaroo mesh pouch. I much prefer the pouch for everyday use, but it's sometimes nice to have the ring sling so that slight adjustments can be made. Also, other people are able to use my ring sling, but when my dad tried to use the pouch with my 8-month-old over the weekend, it was too small for him.
Oh, if it helps, my younger DD is 8 months old, and she was just over 17 lbs. and 27" at her 6-month check-up, so she's bigger than that now. I can also carry my 30-pound toddler in both slings although she doesn't really like to ride in them anymore.
If I were you, I'd probably try a stretchy pouch sling b/c I think it offers a good amount of flexibility but is also easy to use. (Then, if you want another one later, try a ring sling or other kind.)
Just my 2 cents,Stephanie w/ Megan (6/6/03) and Annie (11/10/04)