Which stimulates more collagen, the Syneron PicoWay Resolve or Microneedling with PRP and radio frequency?

Few things to keep in mind. The devices you've listed both induce collagen production (neocollagenesis) but the dependent factors are treatment goals (ie. mature or immature scar revision, aging skin), current health (ie. diabetes, insulin-resistance, malnutrition, cardiac, and respiratory conditions requiring blood thinners, steroid containing inhalers), lifestyle considerations (ie. sun worshiper, smoker, regular use of NSAIDs, regular steroid use), and the provider's experience and knowledge-base in choosing the appropriate parameters with all things considered. Typically, best results are seen with a series of treatment sessions spaced 6 to 8 week apart. 
Best of luck!

A combination approach would give the most improvement. I recommend Ultherapy with RF treatments, lasers, microneedling/PRP or sculptra to get increased collagen, tightening and improve skin tone. I recommend getting a formal evaluation with an expert. Best, Dr. Emer