We moved to Justworks recently and have been happy with them. We considered Gusto on the basis of strong recommendations from friends, but their insurance package for Pittsburgh didn't satisfy. (They're likely totally fine elsewhere or if your company has other needs.)

We used to use TriNet. Moderate ugh - we spent two months with them trying to fix an incorrect 401k contribution and their flow is a bit ... Stale? It feels like using workday.

We use ADP Canada since Justworks doesn't go there yet. Not as smooth as either Justworks or gusto.

We use TravelBank for reimbursements. They're pretty good.

Gusto is an alternative that works well for us.