42 inch or 24 inch?...?

I need som advice!

-I have a 24 inch LG Monitor playable with xbox360 on 1080p, with headset (not turtle beach) Take a look at it below:

http://www.lg.com/us/computer-products/monitors/LG-lcd-monitor-W2453V-PF.jsp

Also have this:

- 42 inch Pioner Plasma Ready HD, where i can play 720p or 1080i. For some research on internet I always uses 720p there. With this solution I can also play with my X31 Turtlebeach headphones. Dont ask why I cant use it on the 24, I just cant, not possible for some reason. Take a look at it below :

http://www.pioneer.eu/eur/products/archive/PDP-4270XA/index.html

My question is, what do you guys prefer of these 2 combinations? Dont talk all about your upset and brag it off. I ask for advice for my setups, and what to choose.

I hope someone can give me a good answere and adivce on this one! Ill have all the connections/cables . Im not a tester so Ill stick too my 42 inch in the meanwhile. I played litte bit with the 24, and I felt the response time was much better, but I dont know.

Since I`m using this Tv/Monitors only for playing Call of Duty series I hope I am in the right please for some useful answers.