You want neither execution nor prison then what do you even want? Forceful administration of drug cocktails that change a criminal's personality?
A better system.
You need to understand that demanding the end of prison does not come alone. Just like demanding the end of capitalism does not come without the end of patriarchy or systemic racism. This entire things is ONE BIG problem with a lot of ramifications and many faces. Everything needs to go away to work correctly.
If you try to build a socialist city without getting rid of patriarchy or meritocracy, you will see the rise of dictators and other type of authoritarians, if you want to end patriarchy without taking into account anti-racism, you will just recreate a form of racism in feminism and thus perpetuate a form of patriarchy and oppression that goes against feminism. If you want to end the oppression against LGBTQ+ without taking anti validism or anti capitalism into question, you will just create an environment were many people like Trans will be more and more excluded from the circles of discussion.
The struggle against oppressions need to be intersectionnal or it can be.
This means that if we want to end prison, we need to get rid of capitalism which throw people in prison, where people go to feel safe, we need to end ableism that pushes people to be marginalized and prevent us from finding inclusive solution to deal with people who can't fit in society.
If you attack a single problem in our society without taking into account the fact that said problem is the side face of bigger or different ones, you will only perpetuate oppression and resolve nothing.
This is why prison do not prevent the repetition of crimes. It's like putting a single 3 cm patch to stop a depressurisation of a space station that suffered a meteor shower. It's useless.
As for immediate actions. First, let's stop putting in jail people who are not likely to commit crime again. Let's take a part of the vast ressources of our Billionnaire friends to help solve the poverty problem in big cities. And let's stop trying to use Prison as torture centers.
Prison have no value, but if they are necessary at the moment, they should definitely not be place where we punish, but places where we isolate.
The term isolation is key. Prison have no value outside of this word. You can find any excuse you want, none will be good enough to justice putting people in a 9 m² chamber, where they are humuliated all day long and where they can't even start to work on themselve.
I've been locked in a room for more than a decade. Not in prison, just because of my condition. I know full way that it can crush ANYONE. No one can heal or change in such an environment when they are humiliated all day long, when they risk their lives everyday, when they are beaten or forced to work without salary.
In fact.. I will be even more extrem, Prison should be part of the SAFEST and most PEACEFULL place in the world.
But.. to understand this, you need to see humans as things that are more than the sum of their actions.
A human is a potential for change, it's a potential for greatness.
No human on earth escape this fact.
But for this to happen, you need to let it happen. If you see justice as a way to punish, you will create a world of oppression. Now.. If you see justice as a doorway for change and redemption, it starts to get interesting.. and you will open the door to utopia.
Look at me. Do you see this system on earth ? And yet, I can tell you that this is how I picture the world. This means that this vision of justice is not only better but also quickly achievable..
As long as we are willing to change how we see the world.