I'm going to lay F2p pures for you.
1. Strength Pure - 40 attack, Highest str possible, 1 defence, 1/11/31 pray (IMO dont ever get pray, but its up to you)
2. Range Pures | Tank - Highest range possible w/ 10/20/30/40 defence | Pure - 1 def, highest range possible | Range 2h (most common f2p type) High range, High strength, High enough attack for 2h of your levels (cap at 40) pretty much use range to mow them down then pull out the 2h for ko | Range/Mage, really useful at the lower levels, probably 25 and below, instead of 2h for ko, you use mage
3. Hybrids - bit of everything, def at 1
4. Rc tali staf pures - High strength, 1 attack, 1 defence, 50 runecraft and tali staff (can be pretty effective from experience, but if you lose that tali staff, you really cannot be fucked getting another 10k tokens from GOP | Positive side to this is that you can go on to be an obby mauler

or pretty much whatever you want)
Umm, these are the only ones I can think of, off the top of my head, and are definitely the most common. I did a really brief layout so if you have any other questions, ask.