This is all based on personal opinion and my powers of deduction based on real life turtle species :) Turtles are awesome :D
1987:
Leo - Map
Raph - Map
Donnie - Map
Mikey - Map
2003
Leo - Chinese striped neck
Raph - Chinese striped neck
Donnie - Chinese striped neck
Mikey - Chinese striped neck
2012
Leo - Diamond Back turtle
Raph - Diamond Back turtle
Donnie - Diamond Back turtle
Mikey - Diamond Back turtle
2014/2016:
Leo - red eared slider
Raph - red eared slider
Donnie - red eared slider
Mikey - red eared slider
2018:
Leo - red eared slider
Raph - Snapping turtle
Donnie - soft shell turtle
Mikey - box turtle
2023:
Leo - Eastern Mud
Raph - Eastern Mud
Donnie - Eastern Mud
Mikey - Eastern Mud