You are asking the impossible question! There is no perfect mouthpiece! Everyone has a different shaped mouth and lips and has different ideas of what is right.
The Holton-Farkas MC is a very standard mouthpiece, the MDC or DC variants are deeper and will give you a warmer tone and more solid low register but you will lose out in the higher register.
There are many different variations of mouthpieces to choose from. There are different rim widths, different inside rim diameters, different depths, different throat (the narrowest bit) widths, different cup shapes, different backbore designs........... Most professional players will have a box full of mouthpieces they have tried and discarded...
Have a look at http://www.horncups.com/range.htm . They boast 2160 different combinations of cup and rim..... Osmun Music http://www.osmun.com/MPC/HornMPC.html have a huge range of different mouthpieces to choose from. Both give you a bit of information about the various aspects and differences.
In the end it is a matter of trying heaps of mouthpieces and narrowing it down over time (remembering that sometimes a mouthpiece will feel great for a few days and then not so great...)
I am sad to say that unfortunately a new mouthpiece is not necessarily the answer to your problem. All horn players from the best downwards split notes. It is more a matter of good technique and years of practice...... You need to develop your technique and breathing. That will assist in reducing the amount of cracked notes and may well give you a more rich sound.
You should consult with your teacher (although given you are asking here maybe you don't feel your teacher is able to answer your questions fully) or organise a lesson with a well respected professional player. They will be able to help you in the right direction with mouthpieces, tone production and accuracy.
Professional Horn player 25 years and teacher at University level.