Okay i first start off by checking what current Slayer assignment i have.
It can get quite a pain if you have something like Gargoyles and you get there, to realise "o noob, forgot rock hammer (again) " lol...
For most types of slayer monster guthans works well if you like healing, and just switch helms to slayer helm/black mask and the weapon to your favoured style.
For all types of Dragons i prefer to melee them, as im noob range so it takes me weeks to do a task lol.. Dragon gloves help with the xp for slayer, but then the bonuses of barrows gloves makes me just choose the barrows. Proselyt armour along with Ancient mace is a good setup for drags, along with super sets and prayer pots. Take a terrorbird/Tortoise to drags if your meleeing as you can bank the hides (if not metals) and keep the dragon bones as there worth quite a bit (4.5kea) last time i checked.
Banshees, Spectre's, basilisks, turoths, kurasks all require special stuff, mostly slayer helm and mirror shield, leaf-beaded weapons as most people do know, but always best just to make sure you have what you need.
The best slayer setup iv used at 125 combat, 70 summ,
Bandos chestplate and Tassets, Fury, Str cape (t), slayers ring, Whip and Dragonfire, Dragon boots and Barrows gloves.
Mostly summoned bunyip to heal me, along with Enhanced excaliber on tasks you rarely need food which is good as you are saving cash, and can get more kills in as you can save banking time.
Barrows Armours do have better defence bonuses than Bandos, but i liked the added str and pray bonus (plus the looks
) of bandos. I recommend if you have the cash, DFS are just sweet for Slaying as its got str bonus, good defence bonuses and looks the part, along with being able to use on drags and wyverns.
I only ever used d'hide on tasks i really had to such as Aquanites and Bloodvelds, so for cheapness and only ever swapped the Bandos armour for D'hide and was ready to own.
Bunyips and Enhanced Excaliber just save loads of food and can really make a difference in tasks. Just check once u get a task, do i need anything special for these because this can really be a pain.
Good luck to everyone and any questions just ask, although im sure you all know more than me!