I actually had a different theory today. We know he's a foundling, and he clearly wasn't part of the Mandalorian culture during the Clone Wars. It's also been heavily rumoured that Katee Sackhoff will have some role in The Mando. What if it's Bo Katan that rescues him?
Logically I can see it going a bunch of directions for different reasons
Bo-Katan furthers the Mandalorian element,
Yoda changes the element of the baby Yoda,
Obi-Wan is fan service but makes technical sense and kinda sets some extra excitement up for his series
Anakin would actually be an amazing choice but is technically way more effort
Ahsoka would be the highest pure fanservice choice and probably induce the most hype for the series but its technically harder to do and would likely lock a bunch of Ahsoka elements down(actress, etc) if she was likely getting used elsewhere later.
standard Mandalorians are most likely.
other Jedi are possible but would be extreme missed opportunities if it isn't a significant enough scene. Kit Fisto for example would need something good to bridge his great EU version with the sad ROTS showing.