Oh you opened a can of worms now LOL. Theres way more than 5 that are regularly popular but I'll try my hand at a top 5 list:
1. Phantom
2. Millenium
3. Trick
4. Laser
5. Charger
I could go on and on but you said 5. Phantom would by far be the most popular, does that mean they are the best? Well they are good and its up to who you ask. There are at least 10 brands that regularly compete with Phantom on any given night and beat them, its all in the tires and setup. Go with what you can get the most support in your area on and that usually means whatever chassis the primary kart shop your going to be dealing with makes or sells as the more things you buy from one place in general the more help youll get. Loyalty to a business and the resulting support to you that comes from that is worth a lot more than shopping around for the best price on everything, at least to me - and Im a budget racer too but its not worth me saving .50 cents on a part going somewhere else than buying from my main shop because of the help they give me. By the way I deal with Competition Karting Inc / Laser Chassis, great group of people but again, there are many people who can help you, and this question on here will get you dozens of different answers because there really is no right answer. Good luck whatever you decide!
-Rowdy Wayne