We suggest the latter, as this unlocks The Good Thief side quest, which will eventually allow you to sell stolen items. To repay Miller Peshek, you can either pay back with Groschen or do him a favor.
Of course, none of this will be possible if you don’t pay back Miller Peshek in Rattay for taking you in and footing your medical bills, so focus on repaying your debt to him first. Part of what makes stealing so effective is your ability to sell stolen goods to certain merchants. Increasing these stats will allow you to get better at stealing, which can help you make money fast if you know where to pilfer. One of the best ways to earn money fast in Kingdom Come: Deliverance is to get good at stealing, whether that be through lockpicking chests or pickpocketing strangers.