The verdict
If you are a small SaaS on a supported billing tool, I'd pick Tolt. The set-up is short, the vendor says around 15 minutes, and the portal on your own domain looks like your product.
If you sell through a shop or CMS, need multi-tier commissions or plan to run a network, pick Post Affiliate Pro. Tolt is not for physical products or many brands and regions.
Both have limits to check. Post Affiliate Pro has tracking request limits by plan, and a 30 day trial without a card. Tolt plans are tied to affiliate revenue, programmes and team members, so budget for the next tier.