The pay scale is the same for FOs regardless of equipment. The company incentivized the 145 and CRJ with an additional $5k bonus due to the SJS happening with the 175...sort of like a consolation prize. Neither is technically "quicker" to captain since you can upgrade into an aircraft you are not currently flying. Impossible to predict what will be junior in 2.5-3 years. Predicting things in the airlines involves too many variables beyond one's control.

Another thing to consider is how well you learn new things. The 175 has a few more "bells and whistles" to manage...more depth to the FMS, autothrust, VNAV, etc. These things sound nice to have, but a pilot must learn to effectively manage them. Pilots have failed transition or new hire training in the 175 due to an inability to grasp the operation of the aircraft or programming of its functions within the allotted training time. Know thyself...and don't take on more than you can chew. The 145 is a bit more forgiving. Factor in your flight experience to this point to help with the decision-making.

One important pro about the 175 is having actual coffee pots.