The Iron Throne Is Her Birth Right
The first reason why Daenerys Targaryen would deserve the Iron Throne is the most obvious one; she has the biggest claim to it, as it is her birth right.
Of all the people looking to sit on the Iron Throne, Dany is the only person that actually can claim it based on her bloodline. Dany remains the sole survivor of King Aerys II bloodline to inherit the throne. Granted, Jon Snow may also have some Targaryen blood. However, he would not be next in line to the throne as he is the bastard child of Rhaeger Targaryen and Lyanna Stark. His claim would be more legitimate if his parents were actually married, but they were not. Moreover, in Westeros, love does not mean that you automatically will become heir of the kingdom.
On the other hand, some may also claim that Tyrion can lay a claim to the throne if it is true he is part Targaryen too. Rumor has it that Tyrion is the son of King Aerys and Joanna Lannister. Nevertheless, just like Jon Snow, he would be a bastard child too and this would mean he would not wield as much power as Dany. When Robert Baratheon took over the Iron Throne after Jamie Lannister murdered King Aerys II, he effectively stole Dany’s birthright from her.