so im lvl 21 and ive tried about 5 or 6 Followers and most of them will go down (sometimes die) if i accidentally hit them like twice i mean cmon

Have you tried not hitting them?

In all seriousness, I don't like followers. They are too weak and get in my way far too much.

The "get in the way far too much" is THE worst. Especially in a dungeon or something, just standing there blocking a doorway or narrow hallway. Gah! I often give up and holster my weapons and pound on my follower until they leave my service, thus causing them to get the F out of my way. Gah!

Yes, I feel like you have to baby them all the time, even if you give them healing potions, awesome armor, and heavily enchanted top-o'-the-line weapons.

They seem weak because there is a bug that prevents them from gaining stats when you level up, so currently they remain in the state they were in when you first met them (or rather, when you first entered the region they are in). If you're on the PC and comfortable with using the console, you can update them by following the steps below:

• Dismiss your follower (Lydia will go to your Whiterun house).
  
• Open the console and target your follower.
  
• Type in "disable" (no quotation marks).
  
• Type in "enable" (no quotation marks)).
  
• Talk to the follower and invite it to join you.
  
• Save the game, exit Skyrim, re-start it (achievements, just in case).

Optionally you can use "getav health" before dismissing her/him and after you re-hired him/her to see how their hitpoints changed. The NPC needs to be targetted for this. The inventory remains unchanged. If they wear a ring you gave them, take it before you split ways. Everything else is fine even when they have equipped it.

Just to give you an idea: From level 20 to 28, my follower gained nearly twice his hitpoints when he was properly adjusted to my character's level at the time.

My girl levels with me. I have the girl from the Azura shirne.

Dunno, I'm on 43th level and drag my housecarls on field trips quite often and they survive nicely. Of course they are kitted out with best gear- comes with a job of being my housecarl
Haven't used other possible followers/mercenaries

Kharjo, the Khajiit follower doesn't level up. I checked with "getav health" on some older files, and his stats remained unchanged. After doing the steps I described above, he caught up with me. I've also tried it with Lydia and the experience was the same: she had very low stats from around the level I first met her (5 or so). You can see by the amount of hitpoints. If it's something like 100-200 and your character is 30+, they didn't level. It doesn't break achievements (or anything else).

Lydia gets all the things I'm not interested in using Plus she's much faster and changing weapons than I am, sooooo she gets the Staff of Zombies. I'm telling you, her zombie casting spell is really helpful. She's actually a huge help in my fights, but yes she's really weak. I suppose I need to level up smithing and make some dragon armor for her?

If you dismiss Lydia to do the ..enable..disable. Where does she go if you don't own the house in whiterun?

My guess is that she will go back to the Dragonreach, up in the Jarl's hall.