Stripe takes payments and put them behind a simple API. No crappiness and 1099 rules of PayPal. No more reconsidering the meaning of life like back when I had a merchant account. The only downside I see is the 7-day rolling batch (deposit to bank), versus the nightly batch from the merchant account, though I assume that is for fraud protection.
Maybe if you're charging millions of dollars, you should use a regular merchant account. If you aren't, I'm telling you now: don't even bother with a merchant account. Just use Stripe.