Preferance

neither, i use a product called EMA plastic weld, I like it alot, though i have to be very careful. There been a couple of time i have got a drop on my thunmf while holding two parts together. Then i find i have a ring melted into the plastic. Very strong stuff.

I have both and use them from time to time and when I do I prefer the Tenax...just seems a little hotter to me.

Used to use tenax, now it's primarily Tamiya thin cement (green cap).

Tenax

For the past dozen or so years I've been using a generic version of IPS Weldon 3 called #1 Pleximent (or Ethylene Chloride).  Works great and is a heck of a lot cheaper than what you will find in most Hobby Shops.  I get mine from a plastic supply house in Kansas City and it comes in pints, quarts and gallons (I usally buy mine in the latter size - paid $22.00 for the last gal which should last from two to three years)

Tenax gets my vote.

Dean

ruddratt

Used to use tenax, now it's primarily Tamiya thin cement (green cap).

Love that thing over Tenax or PW any time of the day.

Ditto on the Tamiya thin. That stuff is pretty amazing. A bit "hot", but good stuff. I use plain ole Testors liquid cement on larger parts.

I have used various brands in the past but now I alway use the EMA plastic weld, but as Bish has said it is strong stuff and if any gets onto the area around the join or under a finger tip it will cause damage, but it does produce a great bond.