Can anyone recommend a good trail bmx bike?

My recommendation is to go with no recommendation Why? Everyone has a different body geometry on a bicycle. Which make some bicycle geometries better matching up to our body geometry. You'll see this especially in road bicycles though this apply to really any type of bicycle. ultimately the more comfortable you are with that position means the more energy-effecient you will feel in that position rather it be on the road or on the trail. It's really easy to tell on a time trial bike though for instance levi leipheimer's time trial form is way different than everyone elses... google image him then google image others, they are all different. Same goes for a road bicycle, Lance armstrong as you can see has always seem to ride the traditional geometry (except for his brief years on Astana/Radioshack, unsure if his madone he was made to ride had a top tube slope but his training bike didnt have it for sure). Now though BMX trail bikes may be more universal to general fitting than road bikes/time trial bikes but none the less different geometries of the bike will have a different match up to your body geometry which will ultimately effect your performance of cornering the trails and keeping good sustainability throughout the trail.

The 2011/2012 Sunday Scout is a great trail bike. Its not over-built, and it has 28/9 gearing, which is great for trails. It also has a 74.5* headtube angle, and a 14" chainstay, both of which give you more stability for trail riding. However, you shouldn't get a new bike just for trails. You'll be fine with a street bike. I've ridden dirt with a 75.5* headtube angle and a 13" chainstay before. Its not easy, but its perfectly possible.