In my 7 months of learning to play, I have bought basically 3 types of chromatic, brass reed, phospher bronze, & stainless steel. My favourite is stainless steel because it has a mellower sound/tone.
All are good, & I have standard 12 hole, orchestra tuned, (which goes down to the 'G' below middle 'C'), 12 & 14 hole, & then I have a tenor, which starts an octave lower than a standard 12 hole.
I would suggest a standard 12 hole in 'C', unless you know you have a specific need, (& spend around £150~200 on it).