A great replacement for ACF and Metabox is ACPT. I find it to be lot better to use, and the developer is quite helpful (they were as well recently on AppSumo).
The fact that users can generate CPT (custom post types) in addition to the majority of the other features of ACF is a big plus.
It will be better if the provider - ACPT works on the integration via a plugin. Not sure how flexible is Cwicly API in terms of that. @Louis
I am not sure if Cwicly should add all the major providers in the core like Bricks did. I feel a standalone separate plugin is better for such stuff. ACF, Metabox, Pods & JetEngine are the major ones and ACPT is the upcoming one. It will get messy with with lot of integrations. Cwicly native filters based on acf custom fields are enough in most cases compared to say something like Jetengine filters.
The fact that Cwicly comes with ACF has been key in deciding to invest in the tool, offering a full suite to create custom WordPress instances. I prefer Cwicly to focus on the best integration of one tool instead of trying to fit them all. Using CPT UI with ACF and Cwicly didn’t bring any problem and is very easy. Plus, ACF will soon provide its own ways to create CPT and CT. In any case, I really hope than in the future, Cwicly will continue to integrate an Advance Custom Field system as part of its offer.
I wouldn’t mind if Cwicly expanded to support more field providers, but frankly, bundling ACF Pro is one of the biggest advantages of Cwicly at the moment. I mostly hope that the ACF Pro bundle never goes away!