(Non legendary) Mine personally would have to start like this
10.Altaria : It is Flying and Dragon and also has a very good base stat for sp defense. It learns a wide variety of moves like most dragon types which makes it good for multiple occasions.
9.Kingdra : It is Water and Dragon type which means it those its weakness for electric but it still isn't super effective. It has a very good base stat range.
8.Druddigon : It is Dragon and very powerful at that. It is good for combos and power attacks. It can be used to be annoying for a base attacker for a team. Use him at your own risk though.
7.Flygon : It is Dragon and Ground type. Flygon is very versitle with its high speed and attack. Ground moves work with all kinds of combinations such as earthquake/ Gravity for flying types. Very easy to train also.
6.Hydreigon : Dark and Dragon make for a mysterious combination of moves we can all agree, and this stands still as well as most dragons. Very high attack and Sp. Attack.
5.Dragonite : Dragon and Flying come with combinations with outrageous damage! Dragonite is a major physical attacker.
4.Garchomp : Dragon and Ground is great for combos just like I said before with flygon except with different stats it makes it harder to train both constantly. Garchomp is a very powerful pokemon.
3.Salamence : Its type is Dragon and Flying which is again really good for physical attack and sp attack. Salamence is one of the strongest dragon types not including legendaries.
2.Axew : Dragon type. I love axew because it is soo cute! he is pwerful as he grows with a large range of moves. You did say my top 10 now didnt you ^-^.
1. Haxorus : I have used him so much! He is AMAZINGLY strong with a base attack stat of 269-432 at lvl 100. This is super strong. His speed makes up for his lacking Sp. Defense. If you have ever used haxorus you would understand my incredible desire to use him over and over and over again ^^
I hope you enjoyed reading my top 10 dragon type pokemon! :D bye bye