Is one class of acid blockers generally considered more safe for long term use? ppi vs h2 blockers specifically.

No clear answer. As: with all medications, the big issue is not the medication but the situation; the dominant issue. Being alive is fantastically complex. Rx meds are only single molecules recommended in specific quantities/time to shift behavior, hopefully toward better. Stomach acid production can vary a million fold/24 hr; pH 7 to pH 1. H2 blocker can ↓ acid 100 fold; PPIs 1,000 fold, of the million range.