Okay, I'll 'bite'. I've written some of this stuff before in other threads, but have crystalised my thinking over time...
I mainly softbait these days, though i've spent probably way too much money on various micro style jigs without giving them a decent effort (sorry Kandrew!!).
I carry both main brands on board, and also some Daiwa Bait Junkies - which are very similar in characteristics to the Z Man Elaztech material and have an incredible action on the retrieve. And I note that big snap legend Rob Parker in Northland is now regularly using Catch Livies which are made of a similar material, and is racking up some donkeys on those (mostly dragged by newbies in 40m by the looks of it).He previously used Z Mans with an enviable gallery of huge fish for his clients. I'm sure he'd get plenty on Gulp but as a charter skipper, you are going to use durable lures...
Anyway, I started out my softbaiting journey on Gulp after witnessing some big snaps caught on them in the workups, and reading up as much as i could about softbaiting when I was starting out. Gulp was awesome at marketing through the fishing mags etc.
I liked the jigging grub in 4" or 6", but my favourite became the Crazy Legs Jerk Shad - which i think is more durable material than the grub (maybe because the fine bits have to be more durable or the can't mould them?) and is a regular go to; closely followed by the Squid Vicious - also seems more durable than the grub. Both have fantastic movement in the water which is something I believe in.
I also have a soft spot for the sinuous 6.5" Nemesis, on which I caught probably my most outstanding 'fish of a lifetime' type fish - a stonker 77cm trev in the Far North. Trevs are supposed to like small baits, but that one got greedy.
Having got to an acceptable bait loss to fish ratio (4-5 snaps on one bait) using the Crazy Legs or Squid Vicious, I often use them a lot over sand and they are fantastic. BUT I don't like them over foul - which points to one of the main benefits for me with Z Man etc - which is buoyancy.
When I tried my hand at fishing shallow reefy areas, I lost a lot of gear to snags because the Gulps sink into the foul pretty easily. I definitely lose way less gear using Z Mans in those situations, so i almost always grab one when fishing shallow. Usually a 5" curly tail which has amazing tail action and a fat body that you can more or less fish 'weedless' on a normal jighead. The bonus with those is when you wind in, you have a chance of a kingie or other predator latching on.
If you believe the experts who talk about snapper taking baits 'on the drop' except when grubbing in the mud or sand, they often point to the benefits of light jigheads and buoyant baits wafting down to the waiting fish, then basically winding in if not taken on the drop. So again, Z Man is a benefit there. But I'm sure many big 'on the drop' snapper have been caught on big Gulps.
Then there is the buoyancy when 'dragging'. Several of my best snapper ever including one of my two 80+cm fish, have been on dragged Z Man Doormatadorz grubs. They tend not to snag on rubble like non-buoyant Gulps. They have incredible tail movement, and the biggies can't resist. To MB's point, i have no idea how many bites I'd get on a big Gulp grub; all I know is that I'll be mid cast actively fishing softies out the side of the boat and just hear the Slammer go off behind me, the dragging rod is buckled over, and a big red is heading for home with the Doormatadorz in its mouth...
Even downsized to the Tamaki Strait with a 5" Z Man grub (usually Motor Oil or Midnight Oil
), the bigger ones usually come on the dragged grub.
Colour
Unlike some people, I do believe colour makes a difference. I prefer the natural Gulp colours - New Penny in particular. But i like the amazing bright orange Z Mans and Bruised Banana, which Gulp doesn't have. I like to check out lures using a UV torch to see what lights up with glow, or plain UV, and bear that in mind when it's overcast, bright, poor light at dawn etc.
Scent
Some days the fish are smashing Z Man on cast and retrieve and I completely forget about scent additives. So I don't think scent is that crucial unless the fish are really not on the feed - THEN I might grab the scent bottle. I think scent must help a bit in dirty water such as the Tamaki Strait.
BUT, one thing i think causes some people to have issues with either brand 'not working' for them is the need to use the right jighead. Try to jam a slim Gulp (e.g. Crazy Legs) on the big OA Lightbulb rib keeper and they'll rip. Conversely, use a Z Man on a Berkeley jighead and they keep getting pulled back off the hook.
Ultimately, I've had days when every cast was a fish on Z Man, and ditto with Gulp. And days when I've been struggling on Z Man and changed to Gulp and bang; or I've been struggling on Gulp and decided to drag a Z Man and bingo. Never say never, I reckon.
And one final point - I think if you're not fishing softbaits correctly e.g. not getting to the bottom or the softbait is not on the hook straight, etc etc it doesn't matter what bait you have on - you won't catch fish. I believe a lot of people who give softbaiting a go, have no joy, and go 'what a load of bull' probably aren't doing it correctly. Which is a shame.