One option could be something like the Dynamic-class freighter. It is designed for two pilots and up to six passengers, and is meant to accept modifications easily, so you can change the shielding, engines and weapons as needed. The stock model is not terribly fast and is only moderately armoured, but it’s known to be a sturdy and reliable ship, and you can make modifications to improve that armour. Its flexibility is its main advantage over the classic Corellian freighters, and if you’re set on a slower ship it may be a better choice (although the Corellian freighters could be made slower if you rerouted enough power from the engines to the shields or weapons).
You could also go with the YT-2400, which is quite a fast ship but still has a strong hull and good shielding, and the available power and hull space to add on powerful weapons. It takes a crew of three (minimum of one) and six passengers, and has a cargo capacity over twice that of the Dynamic-class freighter. Any other Corellian freighter will be pretty similar, especially within the YT-series, so if you wanted an older model like the YT-1300 or even the YT-1000 that would work too. Another Corellian freighter, the YV-929, is very weapon-oriented, but much more expensive. If cost isn’t a problem, this one may be a good choice.
I hope one of those works out!
~ Jacen