There are certainly many reasons why League of Legends is better than DOTA 2. The first one is that the game is absolutely free and is more accessible by the public. The game is enjoyed by more than 4 million people daily. But even though the game is free, it does not make you spend a single penny for additional stuff if you don't want to. So this makes LOL better than DOTA 2.
In my mind, it is necessary to mention that now Dota 2 is absolutely free, if you want, you can check it on the STEAM (Steam is a digital distribution, digital rights management, multiplayer and communications platform developed by Valve Corporation). Next, as you said in LoL you are able to spend your money as you want and actually you can spend nothing. But the similar situation we can see in the Dota 2. If you don't want you aren't forced to buy some upgrades, staff or bonuses. Also i want to mention that Dota 2 is more modern game. It was created in 2012, and LoL was made in 2008. Furthermore I want to say that Dota 2 has held many International Championships and Competitions( The International 1,2,3 GamesCom, Atod 2 and more). There is a very little amount of games throughout the world that can present such index of competitions per year. And LoL isn't in this quantity.
I would like to react to your statement about all those championships around DOTA 2. It is true that there some of these happening at the moment but I think you know the reason for it. DOTA 2 Gained all of it's popularity because of the first DOTA, the game that invented the genre. However, LOL earned people by itself, it is a first game of it's series and it proved that the game was approved by the community. LOL was played on over 80 major tournaments, such as Dreamhack, ESL, MLG, IEM and others. The second reason that I would like to state is that LOL is more user friendly and is easier to play for the beginners. In DOTA 2 it is very difficult to learn all of the basics, what makes you practice with the AI for hours straight. Also, there are more nonessential thing like Items that fall from you after death, denying creeps, and etc. If a newbie tries to play with people right away he/she usually gets beaten in minutes, what results in a defeat, a thing that nobody likes.
First of all I want to mention that LoL was based on Dota All Stars gameplay by Blizzard. The main idea was taken from the Dota too. Secondly, I agree that LoL has done some Championships too, but there is only one reason why? We can explain it that LoL as i said is older, and it has more time to deal with it. However I don't want to highlight this arguments, there is one that is more interesting. As you said LoL is more friendly for newbies. Let's speak about pluses that newbies can achieve in Dota 2. At first if you have played Dota 2 recently there was new update: special mini-game that can teach you basics (how to play and control). Secondly there is special system of searching games (I mean battles). According to this system in the battle it is impossible to see 1st level players(newbies) and experienced players from 10lvl and higher. In other words newbies play with newbies and experinced players play with similar gamers. Lastly about nonessential things like items that fall from you after death, denying creeps and ect. To my mind these "nonessential things" make game more interesting. In conclusion I want to say that LoL is a good game. It is popular in some countries (especially USA). But this game is for fans, like Dota 1. In some period of time it has achieved the highest marks, but that time has gone. Progress does not stand still. And it concerns cybersport. To my mind Dota 2 is the best game in multiplayer online battle arena genre. Thank You for debating.
I totally agree with you, that LOL was based on the first DOTA like all of the other MOBA games. It also has a few different games styles, like minigames in DOTA 2. The last thing I would like to say about LOL is that the game is very popular in USA makes it better for other players. What I'm saying is that the the contingent is way better. There is a major problem that DOTA 2 has that is called Verbal Abuse. The problem exists because the game is popular in Russia, where kids nowadays are not "sweet". Most of the abusers are children below 16. Some might consider this problem a minor one, but for me it is a serious one. By doing a single mistake you can get tons of swearing words falling on you, this causes lots of disruption. Overall, I agree that both Games are good, but for me LOL is way better than DOTA 2.