Exactly 14 years ago this month, I broke up my variable-back T206 set (521 cards) to seek the ultimate T206 run of an all - 
PIEDMONT set.
PIEDMONT Mission accomplished just 11 months later, I then continued on an all - 
SOVEREIGN set. At the same time, I was also collecting
 T206's for an all - 
SWEET CAPORAL Factory #30 set.
I completed the 
SOVEREIGN set (408 cards) in less than a year. The 
SWEET CAPORAL Factory #30 set took me 10 years to complete (468
 cards) when I finally acquired the Eddie Plank card.
One nice  feature which these 3 sets have in common, is you don't have to get the Demmitt and O'Hara (St Louis variations). Furthermore, the
 Southern Leaguers were not printed with SOVEREIGN  or this SWEET CAPORAL backs.
And, here is my favorite T206 card in each of these 3 sets..... 
WOW ! all three of these cards are graded. Ted has gone over to the "dark side"  PIEDMONT
PIEDMONT set
 SOVEREIGN
SOVEREIGN set
 SWEET CAPORAL
SWEET CAPORAL Factory #30 set
 TED Z
TED Z
.