[Smythe1970]

Trying to compile things for my next game.

[Mirikon]

Whatever fits your character's background.

[Tecumseh]

You likely know that there's no best style since you put the word in quotation marks in the subject of the thread. If you're approaching the question mechanically, rather than via roleplaying like Mirikon suggests, then you should look at which techniques best fit your character.

I personally find Counterstrike to be valuable, and by extension Yielding Force (Counterstrike) too, but it's situational and depends on having sufficient Initiative to take advantage of it. Because of this, I like Jeet Kune Do and Karate, but if you're playing a character that uses a weapon then you'll want to look for a style that features Riposte instead. Iaijutsu can also be useful for PCs wielding melee weapons.

I like Kick Attack, since there aren't any downsides, but that's obviously not going to work for a brawler with cyberarms. I also like Pouncing Dragon, but again it's situational.

I see the value of Clinch + Throw but I haven't played with it myself so I can't vouch for it one way or another. Finishing Move is fun but in all the years I had it I think I only used it once, and even then it was unnecessary overkill to show off.

First figure out what kind of character you want. Then flip through the techniques to figure out which would be most valuable for the character you envision. Then cross-reference the techniques you want with the styles that feature them to determine which one will work best for you. If you're not a "story first" type of player then that's probably your best approach.

[Marcus]

I have agree with what works based upon your character. One more favorite recent design is built around kicking and a pair of cyberlegs. I have blast with it.
Kicking jump kick
Throw combos (this takes some thinking)
Two weapon fighting +1 damage +1 accuracy.
Ballestra
Counter attack
ijatsu 
Shadow boxing the parcor attack that reduce enemy dodge pool, hard to use but very effective.
There’s a coulple more but those all are my favorites.

[welldressedgent]

Look for '6000 words on martial arts.' He says jujitsu; but is pretty focused on low str PCs.
Is very fond of the clinch + throw combo. Says the worst are carromeleg and okichitaw.

I'm speculating counterstrike could be excellent because you don't have to overcome your opponent's defense pool.

[Marcus]

Carromeleg is an odd duck for sure, but would never call it 'the worst'.
Two counter attack, shadow block the thing i mentioned earlier, and quick draw. It' very different from the other styles, but it's combination style and it gives you a lot of action options. Knight errant tactical, would be my choice for lack luster Cowboys way, Lone star tatical is a little over specialized in fairly useless crap. It may fir the body guard concept, but the specialization, Defender Has Defended Against
Previous Attacks is on that cannot be universally useful. 

[kyoto kid]

...for the Season 9 rebuild of my Adept concept, logically she would know Kenjutsu as a martial art being a trained blade adept.  The downside is it that the art has no counter attack ability (Counterstrike or Riposte).  The techniques under Carromeleg almost seem a better fit for a Japanese/Bushido styled blade adept, however being a strict Elven/Tir art. it would likely not be taught in any self respecting dojo there.

[The Wyrm Ouroboros]

'Creating your own'.

Honestly, every line of arts has a variation.  There are a zillion different 'types' of judo, karate, kenjutsu and whatever else.  'Hadoken-Ryu' can share 4 maneuvers with the baseline Kenjutsu, but two of them are different, because it's a different school.  Run it past your GM, explain the differences, acknowledge that it's going to be recognizeable as kenjutsu to most people, and as Hadoken-Ryu Kenjutsu to those in the know, and you have a 90% chance of being good-to-go.

I've also come up with new maneuvers for specific styles as well.  Yanagijutsu - 'Willow Style', as it were - focuses on reacting quickly and maximizing defense.  'Willow Bend' reduced the initiative penalty for Full Defense by 3; Willow Sway enabled the use of two Pre-Emptive maneuvers (Block, Dodge, Parry) with one free action (-10 to initiative, can only be done on character's action phase)

So really, be willing to spend 2 points to learn a new art, in order to gain the maneuvers you like out of it.  Shugyōsha has eight, but only has all the maneuvers out of a handful ...

[kyoto kid]

...unfortunately the character is for Missions and they usually don't allow "alternative" rules because of the rotating GM format. Two of the central skills I am interested in are Iajutsu and Riposte but only Wudang Sword (Chinese art) and Carromoleg (TT Tn'N) have both. 

Just seems a bit odd that Kenjutsu doesn't have it or a similar turn the attack on the attacker move, seems it would be a basic manoeuvre for any sword based art.

[Michael Chandra]

Don't forget the quality that lets you get another move outside your starting Martial Arts.

[Csjarrat]

They're all quite karma intensive but if you're only taking one or two at chargen, anything with counterstrike or riposte is well worth looking at. A lot of the others reduce a penalty by 1 or give situational bonuses and aren't really a great investment.
I quite like staff fighting for someone more non-lethal though. Being able to sweep attack to knock down and do damage at same time is nifty for clearing an opening to flee or let the team have an easy shot

[kyoto kid]

...Iajutsu is very useful when you look to draw and strike as a single move.  It is pretty central to Japanese sword technique. 

The only quality I see which allows an extra technique from another art are a couple of the adept Ways which take up most of a characters' karma allowance at chargen.   

[Michael Chandra]

One Trick Pony (Run&Gun):

This quality allows the character to choose one Martial Arts technique they can do without first learning the associated Martial Arts style.

[Marcus]

Martial art, are not qualities, so price isnt a huge deal.