Hey, i'm not really here for competing against others; just wanna sit back and go through a story without much grinding etc?
Any suggestions as to what republic class I should play
You should take companions into account. I would go with Jedi Knight (either one). You have access to two dissimilar companions very quickly (both a tank and dps), which gives you easy options regardless of whether you want to tank or dps by yourself.
The resource mechanic is also really easy to handle. Some abilities make focus go up, some make it go down. It's simpler than having to monitor your bars to make sure that you don't alter your recharge rate.