Actually, while there are a few bummer powers, there are a lot hat can be good, too.
Sonic seems like it would be a very nice pairing with FF.
I wouldn't go Never for the Def bonus. To small a percent to make it worthwhile. Your team will see at best 2-4% extra defense, and you personally, will see a much smaller percentage of that. If you also had holds and confuses, maybe, but since you likely won't, I'd skip Nerve. I'd also skip Spirit, as you likely won't have many powers that can leverage the extra recharge. A lot of FF is toggles, or recharge nearly instantly as it is. And one of sonic's rarely mentioned benefits is it's very easy to get a seamless attack chain with little recharge. I'd probably go with Musculature, but I pretty much prefer Musculature under the vast majority of circumstances. I might, depending on how heavy the end cost of your final build is consider Cardiac, but I don't think you'll see Nerve or Spirit be the ideal choice for this combo.
As for which powers to skip, I'd skip Detention Field (but if you're soloing a lot it can be helpful, just usually decide to put that toy away on teams), Repulsion Field (I wouldn't take this, especially solo, as it requires a team mate to work, and is pretty awful on end), Shockwave, and Dreadful Wail. The T9 is fairly lackluster, and the crash just not what you usually want to deal with. Maybe if it was a targeted AoE it might be worth taking. Shockwave can be useful, especially solo, or if you're really good with using KB in constructive ways, and judging when not to KB at all, but if you just need to keep things at bay the Force Bubble and Force Bolt usually are better tools.
Some people likewise hate the Force Bubble, but it seems less tempting to use all the time for most people, and seems easier to control. If you decide to omit the Force Bubble, then I'd consider adding Shockwave back in.
Hope that helps ya get started. Feel free to post a build if you work on one. Lots of folks here are willing to offer advice.
FF/sonic is good in the sense that sonic makes up for one of FF's big weaknesses - no ability to boost the offensive power of the team.
Sonic is a single-target DPS set that also does -res, and the -res debuffs stack with themselves, even the ones from the same power. A good starter attack chain that stacks -res reasonably well and requires very little recharge is shriek > scream > shriek > shout > repeat. High recharge heavily-procced builds can afford to skip shout and still do roughly the same DPS, but FF does not benefit much from high recharge. Screech is a single-target stun that also applies a long-lasting -res debuff relative to other sonic blasts. Howl is your only real aoe and is great for debuffing large groups at once.
From Sonic, at the minimum you can skip the nuke. Nukes that crash end and recovery have very little use in the incarnate era, and detoggle your mez protection. Other powers that may or may not be skippable, depending on playstyle and the power of your build are shockwave (KB, does not do -res, Force bubble is better for positioning), siren song (helps soloing but not really necessary on high def builds), and Aim (every bit of damage helps, but the damage bonus is small on defenders).
Alpha is tricky. I would go with musculature core myself. Although the benefit for your blasts is minimal, it increases the damage of your judgement and lore pets. I would only consider nerve if it means the difference between softcapping all 3 positions (on you, not other players) and not. The bonus is very minimal even at the VR level because defense boosts are on schedule B. To give you some idea of how weak it is, an SR scrapper would only get +3 def to all with VR level nerve boost. If you must take a defense buff, consider waiting for Agility boost in the next issue, which boosts EndMod, rech and defense.
Make sure to take reactive radial interface, which adds a chance to proc fire damage to all your damaging attacks. None of the other interfaces offer comparable benefit in most cases.
So, I was told that the shields are now an AoE effect so if the team is relatively close together you don't have to individually buff each team member now and I thought I liked the sound of that. I really like FF, I just hated rebuffing an entire team every few minutes. Now that sounds a little less tedious.
I figured I'd pair it with sonic that way when I'm not buffing, I can blast and actually have a largely useful secondary effect. I figure -20% res from most of my blasts will actually translate into a pretty good damage boost for everyone.
The problem I'm having with working on a build is that all the powers seem relatively good to me in both sets, I'm having more difficult deciding what to keep and what to skip in sonic and could use some feedback on what's hot and what's not in the set as, I've actually never played it.
I'm working on softcapping the build positionally and maybe to all types if it can be done incidentally. I'm wondering how important recharge is going to be as I'm debating between nerve and spirit for my alpha. Nerve is actually looking fairly good, because with it I can pretty much softcap an entire team to most level 50 content with my shield and bubble by myself.
On the other hand I'm looking to be able to solo whenever I want too and nerve is slightly less useful to me with the way I build my characters, since I typically build to have a 90-95% chance to hit most +4s.
Any insight would be helpful. Thanks.