Depends on how much you want to spend.
The Eduard set is reasonable in price and comes with pretty much everything you need and then some.
Royal makes one of the best sets for a Sherman that I've ever used, but it is very expensive.
On The Mark makes an excellent set but they can be hard to get ahold of.
Now if this is your first try at PE .... I would suggest you pick up a Eduard Sherman Zoom set that just includes the brush guards. They are the most inaccurate thing in any Sherman kit. The zoom kit is a great way to learn how to use PE without spending a lot of money. To be honest, I only use 30 - 50 % of any PE set I have bought. If the part doesn't greatly improve the final product, I won't use it.
The Eduard Zoom kit is # TP 028 and are called US Sherman Headlight Guards
and should cost around $5.
Hope this helps a bit
Happy Modelling and God Bless
Robert