Pros = Low Combat, most of the time you fight pures if you stay under 10 def with 60 attack, so the need for weapons to hit through defence isnt really required, if you do need defence dragon claws are one of the best weapons in the game for spec and are avialable at 60 attack. But the low combat is a huge advantage. You can take on maxed pures but you dont have to.
Cons = some people thing 60 attack can get boring, the number of weapons is considerably lower then 70 or 75 but the combat lvls that go along with getting that attack lvl and being maxed are quite significant. I would seriuosly only get 75 attack or higher if your already 90 plus str range and 94 mage, along with having a significant cash pile to buy ags.
Pros = well frankly the whip, the whip looks bad ass, i hits bad ass, and defence just doesnt matter when your using a whip. If you want to stay 70 attack you can use the sara sword but i think sara sword sucks dick, personal opinion. You can also use dharoks axe, and barrows melee weapons along with ahrims staff.
Cons = combat lvls bro, all comes down to this if your getting 70 to be 70 not worth it. sara sword isnt worth the combat lvls
Pros = obvisouly the godsword ags, bgs, zgs, all amazing weapons along with the staff of light which is great but doesnt keep over alot. you can still use a whip but if you plan on staying at 75 attack, you cant
Cons = Really high combat lvl your starting to fight near maxed 60 attack rune pures, and decent lvled tanks, along with the rise of turmoil you wil be seeing alot more of them at this lvl of attack.
78 attack and up
Proes = Vesta longsword, Zuriel STaff, Statius War HAmmer, all fucking amazing weapons that you can use the special attacks on. These will give you the huge advantage on the kids with defence with there amazing special attacks. But with this high of attack 90 str if not 99 is a must.
Cons = combat lvls see 75 attack cons but you just farther in to that progression.
pros = Chaotic weapons unless your an all time whipper 80 attack is a no go unless you already have the dungeoneering lvl, get the dungeoneering before you get the attack lvl.
personaly lower the cb the better so 60 or below