Whatever suits your swing and pocket.

MD's seem to get a great write up here and elsewhere. They look nice as well from what I have seen. TM R7 and R7 draw are on offer all over the place just now. Don't suit my eye but expect there performance to be great (I have the TP's).

Look about and get fitted.

Get the right ones for YOU! its as simple as that. Whatever Looks good and more importantly FEELS good! Go to A/G and use them to Trial every set You like! (They are good for one thing! ) Then go to a Pro who Sells the same set you have chosen and have them Fitted Properly, Also ask if he can match A/G's price, Surprisingly some WILL! Credit Crunch and all that!  

I have just changed FROM Callaway B/Berthas TO MD Golf Forged Original Superstrongs

I bought mine off the shelf and had them Retro Fitted to my Specs for £25 ~ Loft and Lies ~ I Kept the Standard Shafts the D/Gold R300 because I loved the Flight Trjaectory and Mid Height they Gave! 

I Have seen a Huge Improvement since Changing I am now even hitting a 3 IRON! Straight!!!!

So I have gone from a set of clubs which cost me £500 new to a set that I picked up for £160 and have not looked Back! They Feel so much Better!  

You'll actually be hard pressed to buy a better set than the ones you have, mate. MX15s are fantastic irons.

Have you looked at Mizuno MX23s and 25s? They'll both be going for a song.