My 2 cents ... My first 'quality' mit was a Kelly ... don't recall the model (but it was black, 32"- I think & cost approx. $150). A truly quality mit, both in terms of performance and endurance - still have it & use it on occassion.
I used the A2403 (32 1/2")for a season. I felt as though it made me a bit more suceptible to getting "thumbed" -a painful & annoying injury. As pitchers begin to throw harder (as they get older) the potential for this injury also increases.
Currently, I am using (breaking in) a Rawlings Pro Preferred J-Series. Very light, comfortable glove and seems to be breaking in well (but quite pricey) - still have not had the opportunity to use it in a game situation which will be the true acid test. But if it doesn't work out, I still have my Kelly to fall back on.
My opinion of the Nokona - they make an outstanding softball mit but their baseball mit seems to break down a little too quick (here again, the rate at which it breaks down is directly proportional to the pithing velocity) - especially for the $200 price tag (CM500).
I saw the Akadema Prying Mantis @ a clinic at a local DI school. Thought it was very interesting. Tried it on and though it felt a bit heavy - seemed like a quality mit that would perform well. However, I was only able to catch about a half-dozen balls (80-85 mph) and the mit was brand new - not broken in. So I can't give a true evaluation of its performance - but I am considering buying one to give it a try during bull pen work as a test drive.