Bunk pontoon trailers are typically more stable, better for towing, but they require deeper water to launch. Scissor style allow you to get under a pontoon with less clearance and allows launching in shallower water, but they are notoriously unstable, so not great for towing longer distance, but sufficient if you only launch and pull your pontoon once per year.
Sea legs are a nice substitute for anchoring and mooring, can eliminate the need for a pontoon lift, but they are limited as to how deep of water you can use them in, and they do add some drag to the underside of the pontoon since they will be in the spray when underway. If your pontoon is under 115 hp, the extra drag/weight is noticeable. They are mounted to the pontoon frame and do operate with a switch. Wind and waves have to be fairly severe to warrant concern, but I have seen pics of overturned pontoons that were moored on Sea Legs in a storm. Raising the pontoon to avoid the waves, raises the profile, and wind can roll it. Not raising it, can allow waves to “walk” it out of place or possibly tip it.
If you only launch it occasionally, or you park it in a marina, harbor or sheltered area where wind and waves are not a concern, they might be ideal. If you’re in a deeper lake with limited protection from wind/waves, I’m not sure they are the best choice. A bunk trailer is preferable if you mount Sea Legs.