Heres a list.

Axe Hut (55 Wildy): Good thing about this is that the axes continously attack you in an inclosed hut, and dont stop for about 10 minutes. Therefor if a high level does come close you got time to finish your axes and then run , plus if you 3/4 item out there, they wont kill you

Rock Crabs: This has been mentioned a bit, good place to train but quite a bit of clicking, also good to save food.

Pirates: South of port sarim near the ice giants, these guys are great, heaps of them and very rarely used on p2p, also they hit low and have decent hp

Black Knights: Traverly dungeon is the way to go on this one, lots of them, and they arent very strong.

White Knights: If you've done recruitment drive, go to fally and kill these, you get experience and kill totals on your knight count.

Tip: Use slayer tasks so you get more than 1 stat xp up.