Would prefer Mendes over him anyday.
There are many other great agents too who are very successful to get great deals and don't push themselves on the media.
Also, Raiola is a bit limited regarding clubs, It is either Juve/PSG/Manu if you are going to big club, the likes of Napoli/BVB to 2nd tier clubs.
Only Manu in the biggest 2 leagues, and they aren't winning trophies any time soon.
You can see it with other eyes.
Raiola has those high profile who can have their packs out several very big clubs. The other clients are less known and aren't really bankable enough to draw attention from big or even second tier clubs.
Mendes has more "range" with his supply. He can propose an option to the very best clubs, the very good clubs, the good clubs, the average clubs. But, imo, Raiola doesn't do any favour to a club to expansion his business. He seeks out the best contract (money for him and player, playing time, release clause) while Mendes can just send his players to the clubs he is linked to. He did it with Monaco, Wolverhampton, his portuguese clubs, Atletico Madrid.
Both methods seem to work out for their clients but Raiola strikes me as having a more "personal" approach for every case.