Designing Kitchens and Bathrooms - Regrout, retile or redo?

I have a small shower stall (35x48x81) that's in a rather poorly ventilated bathroom. Currently there's tile, but some of the tile in the middle of the wall is chipped and cracked. I also constantly fight the mold demons due to lack of venting.

So my question is...is it easier, better, etc. to retile the whole thing, just regrout and replace the tiles that need it or rip them all out and put in a new shower?

Are the 3 piece wall units sold at HD and Lowes and good? Leak proof? Hard to install?

I would like your opinion on what's the most cost efficient way to "upgrade" a shower stall.

Thanks in advance!

Personally, I don't like anything that big box sells. They sell on price, not quality, and a shower is something that should last more than a few years. In a stick built shower, the most important item is the floor/pan. If it is solid, no leaks, that is a good foundation for a good shower. Actually, I would not consider that a small shower, comfortable size. If wall tiles are cracked/chipped, there may be leakage and soggy underlayment. Is it tile over drywall, or a mud base(cement/metal lath)?? If over drywall, the best thing is to tear it out and start over doing it right with duroc or hardibacker.

Personally, I don't like anything that big box sells. They sell on price, not quality, and a shower is something that should last more than a few years. In a stick built shower, the most important item is the floor/pan. If it is solid, no leaks, that is a good foundation for a good shower. Actually, I would not consider that a small shower, comfortable size. If wall tiles are cracked/chipped, there may be leakage and soggy underlayment. Is it tile over drywall, or a mud base(cement/metal lath)?? If over drywall, the best thing is to tear it out and start over doing it right with duroc or hardibacker.

Not real sure what's behind there. I would have to demo a spot and see. I have a feeling I will be starting from scratch, but wanted some opinions before I dive in.

Well you can start with removing those chipped tiles. That will tell you whats behind them. If its a CBU then the cheapest thing would be replace the broken tiles and regrout the shower. If its drywall or greenboard behind the tile then a Rip out as Just Bill, mentioned would be best.