Almost any top name chassis will do, but I would buy OTK (Tony Kart)
as they are easier to tune, and extremely competitive right out of the box, but I wouldn’t buy a Rotax engine package, almost all clubs I know are getting away from that engine. Most big events and classes do run X30 Tag.
Something to consider is your body size, how tall and heavy you are, before you buy a kart you may regret. A little more info about yourself would help us narrow it down.