Whereas in Legends: Arceus I had two starters that I was really interested in, both of which I ended up using on the team (Rowlet and Cyndquil, since Rowlet's my favorite starter and Hisuian Typhlosion was cool), I'm currently pretty uncertain about which starter I would want to use in Legends Z-A.
Despite Grass being my favorite of the 19 types, I've never really been all that into Chikorita due to Meganium's stat spread being more focused on defense than offense, as I'm a bit more of an offensively-inclined trainer. I'll use defensive Pokémon on teams, sure, but I'm not enthused about choosing a defensive Pokémon as a starter. My Johto playthroughs were, save for one, always a decision between Cyndaquil or Totodile. However, considering that the Legends games aren't traditional mainline games and there are different dynamics at play, Chikorita suddenly becomes an interesting option in this environment.
Tepig's an okay choice, not one of my favorites, but given the options we've been presented, it's got a fair shot.
Totodile has some appeal as, of these three, it's the one I have the most sentimental attachment to. Crystal holds a special place in my heart due to it being the first Pokémon game that added a female trainer option and it being the last Pokémon game I played before dropping the series due to peer pressure and being at that age where you feel like you're too old for "kiddy" stuff, which caused me to (at the time) miss out on Ruby, Sapphire, Emerald, Diamond, Pearl and Platinum until a friend made me aware of HeartGold and SoulSilver, which brought me back into the fold. Feraligatr was my starter in Crystal and was my team's powerhouse. Feraligatr's shine has worn off a bit for me over the years since it doesn't really stack up when you have other options, but again, given that these three are our options, Totodile is worth consideration and doesn't seem half bad.
It might just come down to what, if any, Kalosian forms or Mega Evolutions they might have. What interesting type combinations they might have, what the designs look like, and so on.
I'm probably just going to have to say Undecided until we see more. If I absolutely had to pick one, gun to my head at the moment, I'd say Chikorita holds the most intrigue due to it being a Legends game.
If the thread is revived closer to when, or after, the game comes out, I'll post again with a more definitive answer.