You know, doesn't require advanced coaching to be good. Maybe Amazons or Norse falls under tier 1?
Which teams fall under "Tier 1" depends a bit on how long you plan to develop them and how well you can play them.
Next season is Reset Season which is good to start a fast team like Wood Elves and Skaven.
Orcs and Humans are very versatile and bring a bit more "punch" to the field.
If you're willing to develop a team for a longer time and accept that the first games will be very hard (and that you'll most likely loose them) Chaos, Lizardmen and Dark Elves are wonderful, but they all require some coaching skills to play them effectively.
I won't mention Dwarves because you already tried them and I hate Dwarves.