Having flown them both I can say that the 145 is a better handling airplane. The 175 is a less stressful office when you consider the noise and unforgiving airframe rigidity associated with its smaller sibling. The type of flying also plays a role. Think 6 legs, hard stands, and shuttle busses with the 145.

The 145 is a Honda Civic: spartan with wind down windows and crisp'ish handling.

The 175 is a Ford Taurus: softer suspension, a little more power, a little more room, the same gadgets as the big boys, but disconnected handling.

Which one would you like to spend a day in?

The prep work to block-hour ratio will be higher on the 145 as you spend more time between flights with a greater number of legs. Thus the opportunity for anomalies and delay increase. People on APC like to downplay the importance of the aircraft since that attitude is in vogue right now for different reasons. The truth is that you will be spending a lot of time in the airplane. It is your livelihood. Therefore the amount of stress you subject yourself to is significant to your quality of life.

All else being equal I would suggest the 170 series over the older model. But reality is rarely so. Consider your company's base structure and your relative seniority before the airframe. Those will have a bigger impact in your life.