Depends on what you want. Most stakers nowadays are 60 attack, 70+ strength 1 defence. You'll find a fair few, of course, with defence but alot don't.
Personally, I prefer to have a couple of defence levels. You'd be amazed how much 40-45 defence can help.
And, yes. If you've got defence you can still PK and pk quite well. The account I'm in the middle of making (And possibly selling.. for the right price) has 40 defence and it owns the duel arena and does quite nicely at PK'ing (Hasn't got the stats to own the wildy so much, just yet).
So, figure out what type of staker you want to make. The best ones, I feel, are as followed:-
1 defence, 60-70 attack, 80+ strength
70 attack, 30-42 strength, 70+ defence
61+ range, 40-50 defence
75+ range, 70 defence
70attack, 45 defence, 80+ strength
90 attack, 90 strength, 70 defence.
80+ mage (Charge godspell, I dunno what level for a good ancient spell), 20+ defence (I'd suggest 70. Mage can be so random).
Anyone of those is likely to own in the arena if you've got some luck and pick your fights carefully. Obviously 60att, 80strength and 1 defence won't own anyone with 40defence and who's wearing armour.
Really, i highly suggest a semi range tank. Use mith+ bolts (preferably enchanted) with armour off and you'll win quite consistantly. If they're 1 defence, try putting armour on. If they're doggedly trying to take it off, when they do it switch specials off. They've no chance of winning then(Unless they're a whipper...) untill you get into higher levels.
Plus, low level range semi's are quick as to train. Barely two weeks work and you've got yourself a nice account.