I need to add one size to my quiver and I'm just looking for anyone's opinions and/or experience with the following sails in sizes 5.5-5.7 :
Goya Banzai
Ezzy Tiger
Sailworks Revo
Naish force 5
Severne Gator
Naish Supermoto (2015, now discontinued)

This will be the smallest sail I will use with my AtomeIQ 124l - already a stretch but a 100l B&J is not in the immediate plans, but I still want to go out in 25+ knots and my 6.5 is obviously a handful.
Quiver: Ezzy 8.5 Lion3, Ezzy 7.5 & 6.5 Cheetah

Finally, has anyone ordered and sailed with a Northwave sail? northwavesails.com/

I'd go with the Naish Force. I have couple of them and they are great for bump & jump, very stable, easy to handle in huge gusts and light too. It also makes sense to go with Ezzy since you probably own their masts. Ezzy sells mast halves, very useful in many cases.

Given the board you are riding, I'd go with the Goya Nexus if you are leaning towards Goya. The Banzai is my favorite sail, but for that board, I'd get a 5 batten sail.

Is there a reason you want to run a wave sail on a free ride board?

I used a Sailworks Revo 5.4 for bump and jump for 14 years. I really liked the sail. It's really soft with super easy handling. As a soft wave sail, however, the draft would move around a little bit in big gusts. I stepped down to it from a 6.4, which sounds similar to your intended quiver spacing.

As a note, if it's blowing a steady 25+ knots, I'd usually be on a smaller sail. I think 5.5ish is the right step if you intend to get more smaller sails in the future. On the other hand, if you think this will be your smallest sail, I might be tempted to stretch the gap a little more with a 5.0ish. It's a big step from a 6.5, but it would allow you to sail in a much bigger range of conditions. In my opinion, a 5.7 just isn't that different from a 6.5 in terms of range...

I would stay with Ezzy if I were you. It maybe a different model , but it will feel familiar regardless. Anything that makes our complicated sport a bit simpler is welcome IMO. Now the fact that you are asking for a 5.7 and not for a 6.0 or 5.5 tells me that you've already decided to get a 3 footstraps board /wave; freewave or freestyle/ in the future and not a smaller Atom for example. If i've guessed correctly then I would suggest the 5.8 Ezzy Tiger -the classic 5 batten allaround sail you can't go wrong with.

Thanks for sharing advice, preference and why. I'm taking it all in.

To answer David's question "Why using a wave sail on a freeride board?" A couple of reasons for that:
1 - I intend to buy a smaller B&J board maybe next spring and I would like the new 5.x to be a great fit for the board. I will add a couple of smaller sizes overtime to sail high wind conditions. This means that I wouldn't use the 124l freeride board with that 5.x sail anymore - or at least less likely. The 124 AtomeIQ is not a good board for high wind sailing in 5-6-foot swell and that's what I have commonly here. Now, the IQ is all I got and I prefer being on the water than watching from the beach, even if keeping that 80cm wide board on the water in such conditions is a challenge. So, in short I want to buy that sail for an upcoming b&j board but usable on my current freeride as a bridge.
2 - Those "wave" sails seem to have a certain amount of versatility built-in - if I believe the manufacturer's description - that would still make them suitable for some straight speed runs in high wind when control or power can be more easily adjusted while on the water.

This might not be the best strategy but that's all I can afford at this point! So, I'm just a bit skeptical about buying a 5.x freeride sail that I know won't be the best option on a 90-100l B&J board down the road.

Finally, Jacob raises the issue of the gap between sails around that size. This is also something I was unsure. After reading your point, I'm more in favor of a 5.7-ish because this keeps the gaps proportionally consistent throughout my quiver (~14%). I got use to a bit of overlap and that gives me the confidence that I can be slightly off in rigging a sail or I can accommodate changes without having to re-rig something else right-away if the wind changes during a session. My current Ezzy's wide range capability allow that quite well. Conversely, I feel that a 6.5 to a 5.3 / 5.0 forces me to make a commitment to totally different sets of conditions, which at the same time makes it easier to pick the "right" sail!

Why not buying Ezzy's throughout? That makes plenty of sense too, but unless I really have to, I want to try something different. And finally, I am not in love with the look of the Ezzy Tiger - that's a bit shallow as a selection criteria but aesthetic matters to me!

Ady,
Yes, exactly. I'm thinking of something like a 100l Naish Starship!
Ezzy's? I knew you would say that and you are right! ...But I prefer the look of the Revo or the Banzai!

The new Revos are awesome, they feel softer and more sophisticated then the older gruntier ones and I can absolutely recommend them. Their freestyle team rider Phil Soltysiak has been more closely involved in the design improvements and it shows.
Unfortunately though Sailworks and Ezzy use a different mast bend curve , so youll have to buy a different 430 mast-Nolimitz The Skinny or Sumo. Im not 100% positive, but Goya masts may be closer to Ezzy in that respect.
Also is your boom short enough?! If not youll need a smaller boom anyway, so consider that expense too.
goyawindsurfing.com/topics/masts/

And how about Ezzy Elite ! It looks nice and has great reviews!!
www.windsurf.co.uk/test/ezzy-elite-5-7m-2015-test-review/
www.windsurf.co.uk/test/ezzy-elite-5-3m-2016-test-review/

Ady,
I Was also concerned with compatibility and I ask Bruce at Sailworks a couple of days ago about Ezzy mast on 5.7 Revo and here is his answer: "Yes, your Ezzy mast is going to work. They are slightly softer in the tip than the Nolimitz Sumo masts we design around. Its not a big difference, but you will see a bit more twist with an Ezzy mast at the same downhaul tension, or a bit less rig tension at the same twist. Totally usable though."

Also here is what I found on a variety of mast for comparison. All 430 RDM Masts:

Ezzy
Hookipa 91% carbon
Stiffness IMCS 21.9
Curve Ratio:
- 1/4: 62%
- 3/4: 77%

Sailworks
Sumo 91% carbon
Stiffness IMCS 23.1
Curve Ratio:
- 1/4: 63.8%
- 3/4: 76.1%

Sailworks
Twill 95% carbon
Stiffness IMCS 23.4
Curve Ratio:
- 1/4: 63.6%
- 3/4: 76.3%

Sailworks
Joystick III 75% carbon
Stiffness IMCS 21.3
Curve Ratio:
- 1/4: 63.6%
- 3/4: 76.7%

Goya
90% carbon
Stiffness IMCS 21
Curve Ratio:
- 1/4: 64%
- 3/4: 78%

The problem is that the top of the mast bends too early while the bottom and the middle where the batten above the boom doesn't which caues that batten to protrude in front of the mast even at max downhaul. This in turn makes the rotation in transition more difficult and forces you to give the rig a jerk every time after a turn and in my case even a kick to the lowest batten wich was bending like an S otherwise. If those things don't bother you then go ahead. Im currently using a Ka Sails and Chinook masts which a slightly better then Ezzy but still experience those problems when underpowered with min downhaul. I had 2 Ezzy masts which I sold because of that.

Yeah, I'm not ready to repeat this issue again: Last spring, all my Gaastra's had ill-fitted masts... This ended up being the main reason for ultimately switching to Ezzy's.
Looks like the Goya mast is the closet to the Ezzy specs, which probably means the fit would be ok. I'll check with Goya...

Unless I buy a mast to go along (which I won't), this is narrowing down the choice: either the Ezzy or the Goya

Updated:
From Goya:
Question: Can i use other mast than goya for example ezzy mast?
Answer: Ezzy mast is the closest to the Goya mast in bend.