Pros and cons of a conical fermentor

Stainless conical fermentors don't let in light or UV rays and unlike plastic, it's impermeable to oxygen.

Assuming you're talking about a stainless steel conical, off the top of my head...

Pros:

• Technically easier to collect and harvest yeast
• Can be more hygenic (less chance of scratches that can harbour yeast/bacteria)
• Less fragile than glass carboy (but possibly more than buckets)
• If it's pressure rated, you can cap it towards end of fermentation for natural carbonation
• Looks fancier
• Can dump trub and cold break prior to pitching

Cons:

• Cost
• If not jacketed and in a warmer climate, need a bigger fridge to house in for temp control
• Presumably heavier, so not as easy to move around for cleaning, etc