Whereas the CSP only receives two points for travel, the CSR receives three. The OP seems to be in need of assistance with frequent ground travel expenditures.
For buses and trains, the difference between 1.25x and 1.5x might not be huge, but every bit helps, right? I used to use a similar setup, and even those small extras add up. If you travel a lot, 3x points on travel could be a sweet deal, especially if you rack up those points often. The reserve fee is a bit steeper, but if you’re getting way more back in points and perks, it might be worth it. I’d say if you’re really into maximizing rewards and don’t mind the fee, go for the reserve. If you’re more about saving cash now, the preferred might be your buddy.