Kinesis has incredible mobbing thanks to numerous DoT and AoE skills that affect large numbers of mobs. But Kinesis is an incredibly subpar bosser, since the attacks have relatively low lines and low casting speeds. Kinesis is also extremely squishy, even with his Mitigation skill, especially before 4th job. Additionally, Kinesis can stop normal mobs from attacking, but bosses, are immune to his Cheap MapleStory Mesos grabs/lifts/pushback that would otherwise save you from dying.
In fact, the best bossers are arguably some of the Explorers; Heroes have some of the best damage since your attack goes up with Enrage and you have a passive ignore DEF skill, but are squishy. Paladins have high survivability and good bossing as well.
What I think you shoudl do is watch some lower level job vids, don't get caught up in the flashy lvl 100-120 skill videos. You won't be there anytime soon, quick as it still is though. You need to know what 1st - 3rd job skills are before you get the final set.
Demons are good, don't need MP pots so you save a bit of money and after getting third job, you will probably not really need any potions.
Explorers are versatile and share a Cash shop so if you get a permaNX pet or outfit, you can move it back and forth as you like.
Hayato and Kanna are mobbing powerhouses and after you get Kanna's Shinken, you'll be flooded with party offers.