What is the best type of leather for handmade goods (mostly wallets)
For hand working there are a few broad categories of leather. 


Vegetable tanned leather: this tends to be fairly thick and hard, usually cowhide. This is the best option for many traditional type leatherworking projects such as knife sheaths, belt pouches etc. It is normally supplied undyed and takes tooling/embossing well and can also be wet formed to hold fairly stiff 3-dimensional shapes. 
Chrome tanned leather: this is what is most commonly found in garments and furniture. It tends to be fairly thin and supple and is usually pre-dyed and behaves similarly to a fairly heavy woven textile. This type doesn't take forming or embossing very well. 
Bookbinding leathers: a middle ground between the above types, includes pig, goat and thin cow hides. Depending on the type it can take tooling