Lord dirt & Harrily Ford have given you good advice generally, and especially in these two cases:
Stick to a plan and see it through.
and
i always say farm a team you personally enjoy playing with / have fun using,
Always remember that this is a game and the purpose is having fun. For you, especially, since you know you're the kind of person who will occasionally quit, you can't make a 24-month plan and pursue the path that is more resource-efficient. Always questing for the most efficient path to power is almost certainly going to lead you to quit again.
I can create, and have created, a multi-part plan so that someone knows what they want to buy in each different store and knows what nodes they want to farm with each different energy.
But for you, unless you make sure your focus is having fun, that won't cut it.
So my advice, in addition to joining a good guild and telling you to listen to HarrilyFord & Lord dirt, is this:
Think carefully about what gives you the most fun in this game. Then come back here & tell us about your passion, tell us what you love about SWGOH, what bores you in SWGOH, and what (if anything) you hate. Also tell us what characters you feel like you would enjoy having no matter what their abilities are in the game. Are you someone who just really likes the idea of bounty hunters? Or do you love the ewoks? Or hate them?
If we know what you love, we can help you get more of it, but if we just tell you what to do, even if it's a smart, super well-designed plan, that's not going to work. If you could have fun while slowly and methodically following a plan, you probably wouldn't have quit multiple times.
And don't think I'm criticizing you! I'm a deep believer in the "it's just a game" approach. The whole point of SWGOH is to have fun. If you're not having fun then you shouldn't be playing it. Quitting is fine if you're not having fun.
So if you'd like to play, help us help you by telling us what's fun. You quit multiple times, sure, but you've also come back multiple times. What is it that excites you? What do you love?
Tell us that, and I'm sure you'll get some great advice.
