Mine is a toss-up between Phoenix Sylvestris and Cycas Revoluta(yeah I know, technically not a palm). Both are very painful even just bumping into them or trying to weed around them. The tips of the leaves draw blood with no problem.

Washy is the biggest prick here-note to self;don't reach into
the middle of the Washys with your knitted sweater on :o

It's like trying to rip your arm out of a sharks mouth!

This post was edited by jimhardy on Tue, Feb 5, 13 at 10:27

Phoenix palms have been my most painful, although my livistona decorum is definitely the most prickly (the thorns hook and can really grab onto skin tightly, phoenix palms just poke skin).
-Alex

Without a doubt, my most prickly is phoenix theophrasti (Cretan Date Palm).

I had an Acanthophoenix for many years and it had a gazillion spines... very sharp! But aside from the palms with long, thin sharp spines, I would say it has definitely been Trithrinax campestris, though Phoenix theophrastii is close behind.

Reaching into my Mediterranean fan palms is a mistake for sure. Those little spiny teeth are awful. But they can't compare to the trunks I've seen of some palms in the rain forests of Panama, Costa Rica and Brazil! You don't want to lean up against any palm there!

http://www.google.com/search?q=spiny+palm+tree&hl=en&tbo=u&site=webhp&tbm=isch&source=univ&sa=X&ei=MaYRUe2_COXo0gGtpYC4Dg&ved=0CCsQsAQ&biw=320&bih=533#p=0

I find my worst is Phoenix roebelenii, have given up trying to clean up the old dead fronds. Although, Livistona benthami can be like a pitbull on a chain - just don't get too close. I find that's the worst of the Livistonas I've experienced, and most Livistonas are pretty savage. Licuala spinosa is another. On the other hand Phoenicophorium borsigianum has a mass of spines but quite soft. It's all bluff.

I got a livistonia chinensis thorn in my thumb yesterday my vote goes there

This post was edited by miketropic on Sun, Feb 10, 13 at 10:29