Z transform of finite signals
Note that

$$1+z^{-1}+\ldots + z^{-(N-1)}=\sum_{n=0}^{N-1}z^{-n}=\frac{1-z^{-N}}{1-z^{-1}}\tag{1}$$

where I've used the formula for a finite geometric series.

So both your results are identical and correct.

The ROC is $|z|&gt;0$, which is the case for all causal sequences of finite length. Note that in the expression on the right-hand side of $(1)$ there is a pole-zero cancellation at $z=1$, so in fact there is no pole at $z=1$, hence the ROC $|z|&gt;0$.