Whether beginner or advanced I would recommend SGP and Pixinsight.
BUT.....and this is important...….
I would not recommend you try to use either of them to do all they can do.
That is, both these programs are very complex, but they need not be. Simply ignore the complex parts, and use the easy parts. This will get you what you want. Good images of lots of different types of targets.
Let's face it. No matter which program you use, you will have to learn certain things. Learn them on one of the beginner programs, and you know them. They are really no harder to learn on the advanced programs.
I really do not think you can get much simpler than the Batch Pre Processing script on PixInsight (assuming you know which checkmarks to check in general----and that you can find in various tutorials, or just take the defaults). Yes, there may be six different stacking algorithms (whatever an "algorithm" is) but you do not have to care about that. Just use the one that it defaults to. Your images will still be as good or better than with most other programs.
The adjustments you can make with the Screen Transfer Function are, for many beginners, far better than anything the beginner can pop out with any other program. And it is incredibly simple to do.
So, just do the simple things, and ignore the rest of it.
Then, when you have figured the basics, move on to other more complex things.
At some point you will be using things in the higher level program that are just not in the lower level programs.
Why spend the time learning the basic program (which, believe me, will have a learning curve) when you can spend that same amount of time learning the more advanced program? True, after an equal amount of time learning both, you will have only scratched the surface of the deeper program. But you will have maxed out the beginner program.
Is it hearing some esoteric argument here on CN comparing one work flow versus another? Who needs more than one work flow. There are a number of work flows that you can find in tutorials on line that simply work. They work better than what you find in the beginning level programs. You do not have to care that there may be eighteen other workflows to do the same kind of things...….just learn the one that you like. It is really no more difficult in PixInsight than on the other programs. It looks simpler in the other programs because they use more friendly language......and, more importantly, because they only have one work flow, or very few, to choose from.
Is it a budget thing? Really, you cannot beat SGP on budget. PixInsight is more expensive. But, if you are going into the hobby for real, someday you will want it. Why spend $50 to $100 for a temporary thing, if you are going to eventually spend the $250 or whatever? (On the other hand, if you are unsure of how committed you are, do stick with the freeware (or budget stuff) as much as possible......it does in fact work.)
Let me take an analogy from equipment. Is it better to spend $1200 on a mount you are going to use for a year or two, knowing that you are going to spend $2000 eventually? Why not just buy the $2000 mount now? Skip the double learning curve, and all that. (On the other hand, if you already have the $1200 mount, put it to use now.....)
So, back to my old man advice......Skip the "beginning" program" and go right to something that will last a lifetime.