#5 Goranger- Yes, they're goofy, but they're a prime example of suits of early toku and have set the basis for many Sentai suits to come.
#4 Liveman- The first suits to start the "animal head" motif which would become very popular later on with Jetman, Dairanger, Gaoranger and more.
#3 Zyuranger- The definitely one of the most influential designs. The diamonds and dino heads would later be repeated with Abaranger and (to a lesser extent) Kyoryuuger. The design for DragonRanger (NOT Zyu Green) would later go on to inspire other designs like KibaRanger, KingRanger, Shurikenger, AbareKiller, and GokaiSilver Gold Mode.
#2 Go-Busters- Now just hear me out. Go-Busters was an interesting suit design. For one, it brought us a new material, being made out of leather rather than spandex with the straps. They also had a unique helmet design, with the animals and colored sunglasses-visor.
#1 Gokaiger- These were some of the best suits, combining classic elements with a brand new motif. The pirate designs on the suits work great, especially because of the lack of white and the suit and coat design. The helmets also compliment this, with the main five Gokaiger helmets having a pirate hat and Silver's having a bandana design. However, they also mix in a lot of previous designs in as well. They have the "gimmick belt" as I call it. They also have collars and visor shapes similar to the Gorangers. Overall, they're just a really great design, the best in my opinion.