@Mermaid_Ellix First of all, if you have a base game disc manufactured in or after September 2012, or you plan to install even one pack through Origin, you'll land on patch 1.69 regardless. So it's much less complicated to just install everything through Origin. Disc and digital installs are supposed to play nicely with each other, but that's not always the case, so a purely digital install is better than a mixed one.
It should also be noted that some newer disc drives don't read TS3 discs properly. But this should be obvious after you install the base game—if it launches and then throws a no-disc-found error (or fails to install properly at all), you're stuck installing through Origin.
If you own disc copies of all your packs, and a base game made before September 2012 (the newer ones have an Origin logo on the front, the older ones don't; this is only critical for the base game disc specifically), then you can do an all-disc install and avoid Origin entirely. You wouldn't have to install Origin at all, much less let it control your game.
There are two obvious advantages to this. The first is that you won't have to sign into Origin and let it run in the background while you play. The second is that patch 1.69 introduced the pack selector, which lets you disable certain packs when you don't want to play with them. In practice, this tool tends to forget which packs you've checked off or even ignore your selections, forcing you to quit and relaunch when you realize that some packs haven't loaded.
If you do decide to install via disc, do not allow the EADM to control your install when it asks. This is Origin's predecessor, and it will do everything it can to "upgrade" itself to Origin. In fact, many people install while disconnected from the internet, just to be careful.
With a disc install, you'll also need to manually patch the game to 1.67. You can download the Super Patch and then run it after installing the base game, and again after you install all of your packs.
https://forums.thesims.com/en_US/discussion/175477/official-ea-download-link-for-the-sims-3-cumulative-manual-update