SP3 is the latest version of Mitsubishi's ATF. It supercedes SP2. I believe it is more slippery than Chrysler's ATF+3/+4 formulations, giving a smoother shift and longer lasting transmission.
In terms of friction coeficient,
Type F is strong and abrupt
Dexron/Mercon is moderate
Chrysler is smooth
Mitsubishi is smoother.
The use of Dexron will shorten the transmission life.