5) Varia Suit
First Appearance: Metroid (1986)
Samus has utilized a plethora of suits over the years, ranging from Prime 2's Dark Suit (which allows you to traverse the poisonous atmosphere of Dark Aether) to the Gravity Suit (grants free movement in water). By far her most iconic suit comes in the Varia upgrade.
One of my biggest beefs with Other M was that your commanding officer won't let you access your powerups until he gives you clearance to do so. This makes sense for items like the Power Bomb (which could theoretically blow up the whole ship), BUT WHY IN THE HECK DO I HAVE TO WAIT UNTIL I'VE ALREADY BEEN TREKKING THROUGH THE PYROSPHERE FOR 30 MINUTES FOR YOU TO DECIDE "Oh yeah, fire's hot. You should equip your Varia Suit." No crap, Sherlock!
This suit is the only one that makes an appearance in every single game in the franchise, which made it kind of hard not to pick. It also tends to be the suit Samus is typically seen in outside of Metroid. This is her default costume in Super Smash Bros., and any toys (including her Amiibo) tend to feature the Varia Suit.
5) Super Missile
Super missile is just that. A better missile. With it though you can do more damage to enemies, and access areas you could not before! Those pesky green doors have it coming! Plus it's always fun to take something you currently have, and make it better! That's why super missile is my number 5