Exactly. Your friend doesn't know what he doesn't know. And as you say you haven't seen any 5E Rangers in action, so you also don't know what you don't know. So don't waste your time trying to fix something you've never even experienced as being broken in the first place.Meh... your friend is at his/her first experience of RPG, and you want to start by telling them that something is wrong with the game, but you know how to fix it? That's a very sad approach IMHO. Why don't you just let them try play anything they want out of the PHB and then build their own opinion?
Remember that a lot of the talk right now are folks complaining about the FIRST LEVEL of a Ranger... a level specifically designed to be completed in about one session. One single session where your ranger player will probably never even get the chance to compare his abilities to the Barbarian raging twice, or the Paladin healing 5 hit points before everybody levels up and the Ranger starts getting to use its spells.
So at the end of the day... if you really think you want or need to cut off some supposedly massive problem with the game right from the beginning... sure, go ahead and find a variant ranger to use. There are plenty to choose from. But just also know that if you just decide to do nothing (for ease-of-use if nothing else)... your friend will most likely never have a problem with his Ranger character (provided the rest of the group doesn't play a Druid, Eagle Totem Barbarian, Rogue Scout, and DEX-based Battlemaster Fighter, each of them trying to overshadow the Ranger's niche.)