Any game on the market that is currently seeing any real following is more 'popular' than DotA. The reason is quite simple: We are humans, we LOVE being drip fed different types of rewards may them be useful or not, allow for complete free-to-play in different games or to just make sure there's a better incentive to play a game you already enjoy.

DotA doesn't have any of this and the bottomline is as follows; unless you play DotA and DotA ALONE (and this goes with every single game ever existed as well as activity - social or not - ever engaged in), if it is your sole dedication to be active around this game then you'll play it no matter what and ignore everything around it. But what if you have another game that is equally as rewarding (as you are playing it at times when you COULD be playing a game like DotA) at times but also provide you with a feeling of incentive?

DotA needs this to have a steady playerbase - ALL games need this or else they are far easier to be pursvaded to play another game. For DotA the direct comparison is League (I play both games, I can confirm what I have just said 110%) that League is a better game in terms of MAKING me want to come back where as DotA has the infuriating aspect of "I played a game and got nothing out of it". Now I haven't played CS or CSGO so I can't really talk about the buisness model or the droprate of items in that game but as long as it has a frequent droprate of items and some sort of proper league, icons or more general cosmetics (in DotA this would be the UI for an example and announcer, not sure what it would be in CSGO but think back about CoD with the different icons, titles and so on you could have on your profile to give you that cosmetic option - something like that I believe I have seen in CSGO) being more readibly available or have some sort of 'cred' that goes along them in a more visual or sentimental effect than 'random item <insert generic power-fantasy or ridiculus name here>'.

So as long as CSGO follows this principle, it is without a shadow of a doubt more popular than DotA. DotA has the 'unique players past 3 months', not 'recurring' players after all on their fancy 'pay-attention-to-us-please' sign.