At my company, we started off with Stripe since the API's make it very easy to get started, but since then we have added backup integrations with Adyen and Fis. Stripe API's are still the gold standard, but as you have experienced, that vendor lock in limits your options when they decide to jack up prices.
For businesses that do recurring payments/subscription, one important consideration when you get started is whether you can port out the tokenized card data if you do decide to move to a different processor. Definitely don't want to have to ask subscribers to re-enter their card details because the payment details they provided via Stripe cannot be ported.