Does anyone have a favorite payment gateway to use in NetSuite? The only one I've used before is Merchant E-Solutions. Pros and cons to any?

I’ve used Cybersource for a few projects. It’s not too complicated and not only can you integrate Netsuite to accept credit cards, you can also use it to integrate with your website if you take payments online as well.

We use Versapay/Solupay but were looking at MerchantE, any reason to not use them?

I used WorldPay for the UK subsidiaries. Worked fine. No issues.