Approach to building small SaaS products for people with min upkeep

So here's an example problem that you can solve many ways(different stacks, services, pros cons).

* You want a basic interface, that can generate custom emails and you save templates. (Existing services already). Possible this does not need to be a full blown editor that has to deal with HTML security eg. contenteditable/XSS.

* It has auth, SSL, storage. Pretty basic.

My potential approaches:

Goto email that delivers(not spam) is through Mailgun plus 10K/mo free emails that's not bad.

- WP as a base

In the past I worked at a place that used WP as a base, since it has a lot of things built into it. I'm against it because for example above it's pretty overkill, not to mention the vulnerabilities/too easy for a target(since so many people using it, seems like a bad reason) but particularly random plugins you can use and known vulnerabilities like xmlrpc. I also don't keep up with it anymore regarding what changed on it.

But it's an option, it works.

- MyERN stack(current preferred)

I personally would use React for this(why) well I use it daily/like it(separate components). Backend is Node/Express/MySQL, auth is not bad(JWT).

The SSL thing, can have that for free Let'sEncrypt. Assumes you automate the 90 day renewal.

Hosting... I personally use VPS's from OVH, which you could extend further if you containerized them.

- Basic LAMP

The main thing is after it's built, how long does it last for? I can also use regular plain LAMP as well.

And I think a lot of it is personal choice, do you care/how much time do you want to spend on it. Can use Firebase or other services where you don't have to do much "backend wise".

I don't know... it would be cool though to have random little services like this with monthly charges eg. for maintenance/hosting/etc... keep it running. What are your thoughts?

edit: you can also go super "overkill" too with regard to job queues, uptime guarantees, etc...