Upgrading from 2.1.x to 3.1.x

"Sparks" for CI is long dead. A work around avoiding composer is to copy/convert the classes you are using from previous "sparks" into your application/libraries folder. If they are used in more than one app, consider making them into a CI "package". I don't know if anyone has ported the two sparks you mention.

WireDesignz' HMVC apparently works with CI3 (I don't use it, myself). Others on the forum have either ported it or reported that it works.

For both the above, the "addins" sub-forum might have some useful threads.

As for your later contentions about CI & Laravel, there are many who would disagree. If you feel the urge to move to Laravel, I recommend giving Symfony 4 a test-drive, as it looks to be going down a similar road to CI4. My two cents worth, in any case