On a list ranking the LACs in this area (frequently cited here on CC and the only one of which I’m aware) based on academic publication production, Haverford ranks #21, Carleton #31. https://ideas.repec.org/top/top.uslacecon.html
You’d typically find Carleton ranked higher overall in the LAC rankings, not infrequently in the T10, but these are peer institutions so I personally would not make a decision even partially on that basis.
I can’t really say much about either alumni network or relative alumni engagement. But one thing that may be relevant is location. Haverford is just outside Philadelphia and is in the mid-atlantic region of the country. Carleton is in Northfield, MN. If I had to guess, there are probably more plentiful internship opportunities near Haverford.
Visit both. They are close enough on the merits (in terms of Econ and overall) such that it probably makes the most sense to just go with the one at which you’d be most happy with location and fit. My kids would not consider anything in the upper mid-west. The Main Line area of Philly is beautiful and, IMO, ideal in many respects. I’ve not been to Northfield, but people seem to like it. There are better places than Philly for winter weather, but I’d take it over anything in Minnesota absent a compelling reason to do otherwise.