defence pure's are great, but only if you have time to make one and wont slack off.
low defence pures you could consider making are summoning tank's.
these take a long time to make and cost alot but in the end it will all pay off and once you have your bandos/barrows and dfs with a rune mino youll be killing all the pures in multi without them hitting you.
if you want to make a ranged tank "which i've had before"
you'll want 90+ ranged and 70 defence for pking first with torags helm and 94 mage for venge combos
after that get 99 range and 99 defence and amge if you want to. these accounts take time to make but are very good once completed because of your high defence people barely hit you unless they have chaotics and turmoil, als you should consider getting 80 dungeoneering for a chaotic crossbow, also getting rigour will help since it's what? +15% or 20% i'm not sure as i havent got it before, but when you're maxed you can make alot of money in high risk fights, and if ranged tanks bores you and you have 99 mage, use the account as a maged tank