Tongue blocking adds great sounds for the intermediate and advanced players, whereas the whistle method is better for beginners learning to bend. It is possible to bend notes while tongue blocking but it is much easier to bend using the whistle method at all skill levels. Both methods have their advantages and disadvantages. I hear a lot of different opinions on who are the best players or which are the best playing techniques. Everyone and no one.
Opinions are just opinions.
As you play more and become more knowledgeable, you will form your own opinions and those are really the only ones that count. I just got a harmonica holder. I'd like to be able to play while I'm playing guitar. But this thing feels so unnatural. I put any pressure on it.