I'd say there's roughly two different AC "vibes": Pre-Origins and Post-Origins (Origins is the Egypt one). Pre-Egypt is still very assasin focused. While you can bruteforce your way through, it's very clearly not the intended way, and it's a lot harder than doing the stealth stuff. Post-Egypt is far more openworld, choice focussed. You can still play the Assassin, but because they need to allow many different gameplay styles (including ramboing in), levels/areas aren't quite as tightly designed for cool assassin type stuff.

Both versions are good in their own right, but it's really important to come in with the right expectations. Both sets are somewhat similar to other games in their group, with little switch ups.

Basically it depends on what your issue was with AC. Even if they are a little same-y, the gameplay is (can) be very fun, and as a history fan, there's simply no other franchise that's tackled so many different eras in such an immersive way.

Finally, my purely subjective recommendations for a "new-comer" would be:

• The game whose era interests you most
• If you like openworld action RPGs, Odyssey. A fun filled journey with a lot of worthwhile things to do
• If you want a solid assassin game, Syndicate. At least from a gameplay and engine perspective, it perfected the formula