As an autist who suffered quite a bit under my autism, I suspect paraplegic is way worse, especially if you are above avrg IQ autist.
I would take autism over paraplegic even with low IQ, but there you can argue the other side.
What makes the question more difficult is how large the variance in symptoms and their severity amongst autists is.
I can see some good sides to paraplegia though. Everyone has to show you sympathy and help you out, you might get lots of support from the state, no one expects much of you, you might catch a girl with some out of control mothering instinct who is looking for something to nurse or who just wants to virtue signal to the max by having a walking (well, rolling) virtue medal as a partner.
Still, I don't think all those things are worth not walking.
Might also heavily depend if viagra works for you. Think some paraplegics can get hard with some help, which might tip the balance the other way.