Besides the above mentioned
Infowise tools, another example of a paid tool would be Kintivo forms and Kwizcom forms
It allows drag-drop of fields to be displayed in the form as well as branching and conditional logic. It also has a free trial version available.
Kwizcom forms are also easy to build and create for functional/non-technical users.
Not advertising any of these above products, but was one of the developers in the team that created
Also, checkout this link from Sharegate which lists out various Infopath alternatives.
5 Alternatives to InfoPath for SharePoint Forms
However, if you don't want to use paid tool , you can create your own custom forms using various modern frameworks like AngularJS forms or Bootstrap forms (currently in alpha, but works quite smoothly with SharePoint).
You can also create using Office Fabric UI and Angular JS integration. A great example is given here Custom SharePoint Form Using Office UI Fabric and Angular. It uses the
ngOfficeFabricUI framework created by Andew Connell.
If you are not a big fan of any these frameworks, the using SharePoint designer, you can create your own custom forms.
Building Custom Forms using SPD
Personally, I prefer creating custom forms using these modern frameworks as they are very simple, fast as well as provide great degree of control over the flow of data and the UI/UX experience. Also, as SharePoint provides RESTful interface to most endpoints, its easy to integrate these forms and their control their behaviour and event handling.