Sorry for the long post, I always feel like I get too long-winded when I'm writing stuff online, but I have a hard time explaining my thoughts without going into detail
"if your synergies work you win and its bad for your opponent. if they dont you lose and its bad for you."
Is that genuinely an experience you find yourself having?
I know I wasn't the target of this question, but just to give an example of my personal experience as a very mediocre player at best, this happens for me quite a lot. Not all the time, but in a very general sense I would say that that's how it works for me a lot of the time. If I get all (or most of) the buffs off on a key unit they will perform extremely well, at least for that turn and barring terrible dice rolls. While the small group of people I've played with don't complain a lot about Seraphon, they still don't enjoy having key units obliterated by a fully-buffed Skink horde, Carnosaur, Stegadon, etc. For example, in my most recent battle report I told how I was finally able to legitimately win a battle against the Ironjawz with Gordrakk.
However, in situations where I'm forced into an engagement without any buffs, such as when Orruks or Idoneth have repeatedly been able to charge me turn 1, or when your buff heroes have been sniped after turn 1-2 by shooting armies, I can personally say that against any units designed to hold their own without buffs, or against comparable units who do have their buffs up, they die in droves. Even Saurus. And unlike a lot of other armies that die easily, we don't have any abilities that punish enemies for just charging and fighting us. No mortal wounds dealt or fighting upon death, no participation in activation wars, so we basically just wither unless we A: get our buffs up and B: get to hit first.
So in general, if I'm running an infantry-heavy list and I don't get my buffs off before getting into combat, I generally have a bad time. If am able to both get my buffs going and get into combat first, I generally do quite well, although generally no so well as to cause my opponent to feel like we're totally OP.
So I do agree that overall we have *relatively* weak warscrolls because they were intentionally designed to be buffed. HOWEVER, there are some units that actually do very well without buffs. In my personal experience, units that I never have good luck with unless fully-buffed are:
Skinks, Saurus Warriors, Saurus Knights, Carnosaurs, Terradons, Ripperdactyls.
Units that I've seen able to perform quite well without any buffs are:
Salamanders, Stegadons, Bastiladons, Chameleon Skinks. I would also place Kroxigors in this category if it weren't for the fact that they need their one +1 to hit buff from being near Skinks to do well. When just near Skinks, with that +1 to hit they dish out a surprising amount of damage and aren't all that easy to kill. They're basically our only "elite" infantry option, comparable to Orruk Brutes (arguably better) but unfortunately not battleline. I think more people should consider taking them
In summary: I've found that our battleline units have pretty bad warscrolls and don't do well without their buffs, but with buffs they do quite well. I generally agree with the opinion that Seraphon have weak base warscrolls but get pumped up to crazy levels with all the buffs we can stack on them. However, this isn't true for the entire army. As for whether we're not fun to play against, I really think it's just the very specific Fangs of Sotek build with tons of magic, teleporting Skink hordes that also get overwatch and have a chance to retreat from a charge, and Salamanders waiting to nuke your backline if you don't play defensively that people complain about. I've won games with Thunder Lizards and Dracothion's Tail that were quite close and no one complained about those lists, even when I had Lord Kroak. I have yet to win a game with Koatl's Claw, though. Non-teleporting Saurus just seem bad, as much as I would prefer to play them that way. I haven't used a Knight spam list yet.
But I personally think that the AoS gameplay style is mostly to blame for shooting/teleporting armies being so un-fun to play against. Whenever someone asks how to deal with a powerful or annoying unit or army, the answer the pros give 99% of the time is "ignore them, run from them, win on objective points, just let their good stuff kill your units and hope you can rack up enough objective points by running away elsewhere."
If the different battleplans were less about "sit a unit on this part of the map to score points" and more about accomplishing a specific goal during the game then I think you would see both a lot more list diversity and a lot more variety in which armies are doing well. I know that objectives are a core part of Warhammer gameplay currently, and I can't say that's really a bad way to play, but it certainly does mean that being able to stay *out* of combat and control the board is almost always better than being good *in* combat, which to me just doesn't sit quite right with the idea of a wargame with armies of miniature soldiers who are supposed to, you know, fight each other. If your army is stuck marching forward trying to claim ground while your opponent can just pop up here, there, and everywhere, shooting your units down while taking little damage in return, you're going to be very frustrated.