Before narrowing down to a single name for Red John, let us agree on a few facts/ motifs of the show.
1. The obvious suspect is NEVER the culprit.
2. There are always red herrings.
3. Most episodes involve a complex sub-plot within the obvious, bigger plot.
4. The show, like any other show, is likely to use, and does, top notch actors (I.e. actors with serious creds from other shows on television) for key roles.

In the light of the above, let's look at what we know about Red John.

1. He is omnipresent. Even for an accomplished criminal, the extent of his crime is massive. He is seemingly everywhere.
2. He recites Tyger Tyger to Jane. 'What immortal hand or eye/ could frame thy fearful symmetry'.
3. Jane's list of 7 suspects matches his own.
4. There is a definite connection between Red John and Visualize.

All this points to the fact that Red John is not one person. Red John is a gang, a cult, comprising possibly all 7 people, headed by Bret Stiles. 'What immortal hand or eye/ could frame thy fearful symmetry' is an allusion to a tiger's many stripes- that an artist, were he to attempt painting, could never get right because there are so many.