I have a few around here somewhere and used them when first diagnosed w/
COPD (now diagnosed as not copd!). Anyway... they pretty much work the
same way and are so basic that probably no one of them could be
considered 'better'. (Unless they make some hi-tech one I haven't seen!)

I don't use them unless I call into the doc for Prednisone or Pancof and
the nurse wants some numbers. What they tell me I already know... I am
not moving air! Early on, using one would give me an idea of when I was
simply wheezing and when I was in more serious trouble...

*** It is good to become familiar with 'your' numbers though... both
good and 'bad'. And the peak flow meter can give you that.

Polly

My favorite is a Healthscan "Assess".  It has the scale at a right angle to
the mouthpiece and large enough numerals for my failing vision to actually
see.  I've tried some of the in-line models, and don't care for them.  That
said, there are some really small in-line types that fit in the pocket or a
purse--great for travelling.

As I'm sure you already know, these are each individual's "personal best"
reading rather than an absolute scale, but it can be a valuable and
objective tool to keep track of trends.

http://www.allergyasthmatech.com/allergyasthmatech/product-detail.asp?CategoryID=137

Mine's called a "mini-wright"; comes in a cardboard tube, it's about 8" long,
very reliable, quite cheap I think.  Had it for a least 5 years and it still
works fine.  Mechanically it's very simple.  I don't use it all that often, not
really unless the doc asks me to monitor myself for a few weeks.

I think PF meters are of some use in spotting when symptoms are worsening.  
But I wouldn't spend a lot of money on one - I don't think an expensive
one would do any more than a simple one.  Can also be useful if your doc
changes your treatment and wants to monitor effectiveness of the new
treatment.  The trouble is, this often falls down because it's very hard to
motivate yourself to take the reading every morning and evening, you tend to
do it for 2-3 days and then forget and end up "filling in" the readings to
show the doc.  We've all done it!  A bit like trying to stick to a diet ;-)

In my opinion it's well worth getting your doc to give you a lung
function test including spirometry, lung capacity measurement and
histamine challenge test.  This gives a lot more info than just the PF
meter.

-- gumbo

I bought a cute little peak flow meter by Piko-1.  I noticed it on ebay
and then bought it on-line elsewhere for about $30.  It has a watch
battery and measures both how fast you can breathe out and also how
much your lungs can hold. I really like it.  An allergist told me I had
asthma and scared me by telling me that my lung functions were not up
to what they should be and insisted that I take 3 kinds of medicine
that I later discovered were steroids and also get a whole raft of
allergy shots.  After much searching on the internet for numbers for
someone my size and age, I found out that my numbers are just fine.  I
did make changes in my lifestyle especially in the bedroom to vanquish
the dreaded dustmites as much as possible.  I am back at the swimming
pool again and hope that his dire predictions of monster mold attacks
won't come take place.  Get that pico peakflow meter and protect
yourself against charlatans.