Depends if you want to change the paint often. Powdercoating is more resistant to chemical paint strippers and may be really difficult to take of if you don't like the outcome or change your mind later on. On the plus side it's more scratch resistant than paint, but then again it can only resist so far. You want to minimize the amount of sanding that occurs on the surface of the frame too, especially on butted tubes as they can be fairly thin to start off (if you're re-painting the same frame often).
I see you've already stripped the old paint off your frame. For others who are thinking of powder-coating, some outfits will recommend (if not insist) that the frame be sand-blasted prior to powder-coating, as this is common in the industry - to create a key or a grab for the coating. Don't do it! Bike frames are very precisely engineered and only have the bare wall thickness necessary for the load its designed to bear. Sandblasting takes off too much metal and unevenly too at that, and you can't see the damage to the frame with your naked eye. Some areas may have been reduced to paper-thin and you won't be able to tell until it crushes like a Coke can later on. A sand-blasted frame is a compromised frame... it's stuffed! (Buyers beware when buying a repainted frames that have been blasted).
Also watch out for the quality of powder-coating, as there's various grades. Some outfits can only do heavy industrial quality and it can be pretty rough with visible "orange peel" texture. Some places can keep things fine if they see its a bike frame, home appliance quality (as in white refrigerators or ovens). So it pays to ask and better yet, see some painted samples of their work before hand. It is also harder to achieve a high gloss finish from powder coating. If you want high gloss, go for automotive acrylics or two pot epoxy lacquer... but it will cost ya...
Finally, make sure to tape the areas you don't want paint on (powdercoat is a real pain to take off even with a sharp knife once it's on) - BB threads, bearing seats on the head tube, exposed inner wall areas of the seat tube. Don't use masking tape as these just burn when they cook the powder coat in the oven. Ask them for some foil tape, they should have this stuff. Don't trust the painters to mask these areas for you as they don't necessarily understand bike assembly.
One thing to be aware of... the baking process can get quite hot. The heat treatment in High Tensile Steel frames or Chromoly frames are usually not affected by the baking heat in the powder-coating process. Aluminium frames on the other hand?... well it's iffy. Personally I wouldn't powder-coat a high performance aluminium frame because the baking process can change the heat treatment and weaken the frame. So generally, I have powder-coated a few of may son's free-style BMX frames, but I would only lacquer MTB aluminium frames (6061T6 or 7005T6 material).
Cheers - Pocko
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