As I struggled a bit to find relevant information, I post on this forum some useful tips, about the choices available for contact forms.
1)Rapidweaver default contact form page: it is simple and good. As my site is multilingual (I use the RWML stack by stacks4stacks) I thought to look for a stack instead of a page, to make the contact form.
2)HTML form stack (by doobox): very easy to use, if your need are very very basic. It didn’t suit my needs as I needed to collect very specific information from my clients.
3)FORMULATE by stacks4stack: definitely the best solution in my case. Easy to use, it doesn’t use PHP or SMTP or HTML but instead an easy internet service that is free to use (I used formspree.io).
3)If you need a more complex solution: FormsPlus by Chillydog. I bought it and tried it. If you install it you need to carefully read the instruction and pay attention to correctly set it up. It is more expensive, around 50 euros, but definitely a more powerful option. I actually didn’t need all this power. Also I had to connect to my host (A2hosting) and set it up to use a more recent version of PHP. I think I was on 7.2, and the minimum required for the stack is 7.4. Again not difficult, but I didn’t even know what PHP was so I had to check about it, connect to the host etc… I actually ask for some help to the developer, that was super king and explained what I did wrong super fast.
4)I know there are similar stacks from one little designer (Super forms) and Yabdab (FormSnap). I didn’t try them, but I guess they are good, if you need a more powerful solution.
So if your needs are medium, you don’t want to waste time, pay little money, and without need to check about PHP version or other technical stuff, to me FORMULATE is the answer.