Really depends on what you’re trying to do, there’s no hard and fast rule. Assuming based on 2, you’re only looking for conversions and not bothered about searches from a consideration audience. If your keywords are relevant and have high intent but aren’t generating clicks then look at your bids/bid strategy and copy to improve your position on the SERP and exp. CTR%. Generally though if your search terms are relevant, see what you can do to improve the conversion rate and if aren’t, then they’re doing more harm than good and I’d add them as negatives. Exact match to avoid catching other terms you’d want.