I personally use QKSMS, which isn’t perfect, but it’s all I’ve been able to stand since Signal dropped SMS support.
This RCS stuff scares me a bit, because it sounds like it will function over a data connection and not be nearly as universal of a standard as SMS/MMS is. There are already a million such apps and standards if one wants to use data for messaging. Trying to sneak it on top of SMS is very annoying. If I use my SMS app, I want my messages to be sent as such. Getting a surprise data bill shouldn’t be a fear.
If I wanted a messaging app with advanced features, I wouldn’t be using the SMS app that came with my phone.
QKSMS hasn’t been maintained in a while, besides one update at the start of 2023.
It may be better to go with, and I personally just use, PartisanSMS which is an improved fork of QKSMS.
That looks like it’s stopped being developed too. Connect You, a Contacts app originally, is adding SMS support— but right now it kind of sucks, so we probably want to wait a bit for development.
RCS does function over a data connection (and WiFi!), however unless you’re sending large files over the wire it’s probably not going to have any effect on your data bill. Text messages are a handful of kilobytes large at worst. SMS/MMS have lots of issues to do with security and capability, and most handsets support it in some form already.
Not everyone has a large data plan. I am very aware of how much messaging taxes my data plan: the entirety of my data is already used by it.
