It's interesting that NEXUS is just for people and costs $50 each, good for going either way between US and Canada by land, sea, or air, and includes use of Global Entry kiosks when entering the United States
via Canadian Preclearance airports, which means the kiosks are actually in Canada . It also permits entry to the US via Global Entry from other countries, and now it also includes use of SENTRI lanes from Mexico (all this from the
CBP website).
SENTRI is only for Mexican land borders, only into the US, includes a car as well as people, and costs $122.50 each. However, it works as NEXUS when entering the US from Canada (but presumably not the other way) and includes Global Entry privileges if you're a US citizen or national.
Both are good for 5 years and include PreCheck, inasmuch as you can fill the card number into the KTN field.
NEXUS would seem the most cost-effective, but you have to have the interview at a NEXUS site, which are only found along the Canadian border (e.g., Blaine and Seattle in WA).