There's 2 things to note in speed gear.
-Speed (obviously)
-Sprint Stamina
Speed is important but also Sprint Stamina is. If I were you I would choose the pieces of equipment with the highest Sprint Stamina and speed.
*EXAMPLE*
+5 SPEED AND +1 SPRINT STAMINA
+2 SPEED AND +7 SPRINT STAMINA
+4 SPEED AND +4 SPRINT STAMINA <=====Best choice